Only semi-glossy (light matte), glossy and Plasma Deposition coating plus LED PWM Dimming (Side Effects) Free/Super High Frequency using 2560x1440 monitors without really obvious overshoot ghosting, tons of quality control issues and good color presets will make my list.
I included =DEAD='s (overclock.ru reviewer) photos since they are excellent and were taken with the same camera settings which makes it easy to compare the displays aesthetics.
If a monitor is not on this list it either has not been reviewed properly, been reviewed at all or is mediocre. All monitors suffer from regular quality control issues: back-light bleeding and pixel issues (dead and stuck pixels).
Worst 27" 2560x1440 Monitors
The single input monitors are delay free, only have brightness controls, do not have a menu with color controls and ONLY work with PC's. The multi-input monitors can not overclock, or drop frames when overclocked which makes movement look stuttery/laggy, but can be connected to consoles.
Warning: The 144hz 1440p AHVA Panels have very poor quality control and tend to suffer from back-light bleed and yellow or brown stains too.
Single Input Matte:
Acer XB270HU (144hz matte AHVA with G-Sync)
Crossover 2795 QHD (more information)
Multi-Input Matte: Gaming Priority=Blue Image Quality=Purple
#1 #2 Eizo FS2735
The Eizo FS2735 uses a 27" 2560x1440 resolution 8 Bit AUO AHVA panel, a nearly grain free matte coating, excellent color presets, a high quality matte black bezel which increases the perceived black depth*, fast pixel response times and a 144hz refresh rate. Free-Sync (AMD GPU required) works from 56-144hz/fps, eliminates tearing and lag, it is the only AHVA Free-Sync monitor with back-light strobing, and has excellent 1080p scaling which makes it the best all around 27" 1440p AHVA 144hz monitor for PC and console gaming, and watching 1080p content.
*Dark matte grey bezels increase the perceived black depth even more.
#1 #2 Viewsonic XG2703-GS
The Viewsonic XG2703-GS uses a 27" 2560x1440 resolution 8 Bit AUO AHVA panel (M270DAN02.3), a nearly grain free matte coating, has excellent color presets, a nice dark matte black bezel which increases the perceived black depth, very fast pixel response times and a 165hz refresh rate. G-Sync (compatible Nvidia GPU required) works from 30-165hz/FPS, and eliminates screen tearing and lag. The Viewsonic XG2703-GS also has ULMB (back-light strobing, excellent 1080p scaling unlike the Asus PG279Q, and superior 60hz overdrive with less overshoot ghosting than the Acer XB271HU. The Viewsonic XG2703 is the best all around 27" 1440p AHVA 144-165hz monitor with Nvidia G-Sync for PC and console gaming, and watching 1080p content
#1 #4 Acer XB271HU
The Acer XB271HU uses a 27" 2560x1440 resolution 8 Bit AUO AHVA panel, a nearly grain free matte coating, has good colour presets aside from a preset green tint, a frame-less casing with an inner black bezel which decreases the perceived black depth, fast pixel response times and a 144hz refresh rate. G-Sync (Nvivida GPU required) works from 30-165hz (144hz is the default maximum refresh rate but it can be overclocked to 165hz), eliminates tearing and lag, but Lightboost is limited to 120z. It also has an HDMI input with superior 1080p scaling compared to the Asus PG279Q, but also slightly more overshoot ghosting at 60hz.
#2 #4 Asus PG279Q:
The Asus PG279Q uses a 27" 2560x1440 resolution 8 Bit AUO AHVA panel, a nearly grain free matte coating, has good colour presets aside from a preset green tint, a matte black bezel and an inner black bezel which decreases the perceived black depth, fast pixel response times and a 144hz refresh rate. G-Sync (Nvivida GPU required) works from 30-165hz (144hz is the default maximum refresh rate but it can be overclocked to 165hz), eliminates tearing and lag, but Lightboost is limited to 120z. It also has an HDMI input which allows it to work with external devices like consoles, but has inferior 1080p scaling which makes it an inferior choice for an all around gaming monitor compared to the Acer XB271HU (best G-Sync monitor) and Eizo FS2735 (Free-Sync monitor).
#3 #3 Asus MG279Q:
The Asus MG279Q uses a 27" 2560x1440 resolution 8 Bit AUO AHVA panel, a nearly grain free matte coating, has excellent colour presets when the Racing mode is selected, a high quality matte grey bezel which vastly increases the perceived black depth, fast pixel response times and a 144hz refresh rate. Free-Sync (AMD GPU required) works from 30-90fps, eliminates tearing and lag, but the has >10ms delay when not set to 144hz.
#3 #2 Crossover 27 Fast 144:
It's the Crossover version of the MG279Q with slightly slower pixel response times but no overshoot, an inferior dark matte black bezel instead of a dark matte grey bezel, and it can't be returned or exchanged easily since it must be ordered from South Korean eBay sellers or online retailers.
#3 #1 Crossover 27V & 27100Q
The 27V, 27100Q and 27 Fast 144 are Flicker Free, can be considered delay free (3-5ms delay measured with the SMT Tool by Playwares), use AHVA panels (AUO's version of IPS), have fast pixel response times, excellent color presets and support AMD Free-Sync (assume 40-75hz or 30-90hz with the 27 Fast 144) or 75 (27V), 100hz (27100Q) or 144hz (27 Fast 144) when connected to Nvidia cards. It might be possible to increase the Free-Sync range with the mod mentioned in this thread.
List of cards which support Free-Sync.
#4 #2 LG 27MB85R: It has excellent colour presets, a matte grey bezel, low input lag and fast pixel response times. The LG does not use PWM Dimming while the Qnix/X-Star PLS panels do, as well as at least three different panels. The 27MB85R-B is the best since it can be hardware calibrated (colour corrections are saved internally and can not be reset by the video card or games), has a matte grey bezel which vastly increases the perceived black depth, negligible input lag, very fast pixel response times and excellent colour presets. Competitors like the GW2765HT has a frame of input lag, a perceived black depth ruining glossy black bezel, worse colour presets, no hardware calibration and slower pixel response times. The 2014 edition of the PB278Q has a matte black bezel which ruins the perceived black depth when the monitor is not placed in a very bright room, and awful colours and contrast when the colour controls are unlocked. The Dell U2715H has slightly worse colour presets, can't be hardware calibrated and has a inner black bezel which ruins the perceived black depth since it is not actually frame-less. (example).
#4 #1 Qnix QX2710 Multi Hot
The Multi Hot is pretty much the same as the QX2710R, but uses a perceived black depth increase brushed dark matte grey bezel while the QX2710R uses a glossy black bezel which ruins the perceived black depth, but has more inputs. The Multi Hot can be overclocked to 87hz without dropping frames via Dual-Link DVI; the higher refresh rate counters the 20ms delay and reducing screen tearing if playing without V-Sync which makes it a better choice for PC gaming than the 2014 edition of the Asus PB278Q/PB278QR, and the Multi Hot does not suffer from contrast and color accuracy loss when using the color controls.
#4 #2 Asus PB278QR/2014 PB278Q: It is PWM/Flicker Free, delay free unlike most of the multi-input 1440p monitors and is noticeably faster pixel response time wise (ghosts less), but it has slightly worse colour presets than the AOC Q2770PQU, BenQ BL2710PT and LG 27MB85R. When the colour controls are unlocked (switch the Colour Temperature setting from Warm to User), the colour accuracy and contrast are reduced to the point of ruining the image quality.
#3 #3 AOC Q2770PQU & Q2775PQU: I preferred the BenQ BL2710PT I reviewed over the AOC Q2770PQU I tested since the BenQ had slightly better color presets and less corner glow, but the AOC is worth trying out first since it can use glow free panels. The AOC's Medium overdrive setting provides slightly faster pixel response times than the BL2710PT, but suffers from a tiny bit of overshoot ghosting and they have similar lag which is why they are tied for gaming.
The Q2775PQU has slightly faster pixel response times than the Q2770PQU, but very similar image quality and a 20ms delay.
#5 #2 BenQ BL2710PT
#6 #4 BenQ GW2765HT
The BenQ GW2765HT has faster pixel response times than the cheaper multi-input Qnix AHVA (QX2710R & QX2710 Multi Hot) and PLS (QHD2730R), can be returned and exchanged easily in most countries, but can not overclock, may have slightly worse colour presets than the Qnix monitors, and more glow than the QHD2730R PLS since PLS panels tend to glow less.
Glossy Single Input: Able to overclock up to 120hz (96hz minimum)
Overlord Tempest X27OC
Zalcom ZM27Q1 (it's a non-overclock-able panel with nearly identical performance)
The MOTV M2700, Overlord X27OC and Yamakasi Catleap all use the same overclock-able, glossy 8 Bit LG S-IPS panels and offer nearly identical performance. The MOTV is only available from Green-Sum's store.
The glossy Qnix QX2710 & X-Star DP2710, have slower pixel response times and the gamma rises when overclocked, but glow less than the IPS panels when viewed head on. The ICC profiles provided in my reviews correct the high gamma. The newest batch of glossy Qnix & X-Star's use LED PWM Dimming/flicker back-lights and a different Samsung PLS panel which remains unaffected colour wise when overclocked.
Glossy Multi-Input: Crossover 2720MDP/2730MD
Plasma Deposition Coating:
Crossover 27QW Sawkwa and Crossover 27QW DP
Hazro HZ27WiDP it is not PWM free but has an 842hz frequency which is 4x higher than normal.
iiyama XB2779QS: minimum brightness is 170cdm/2
Wide Gamut: Monitors for work with programs which support colour management. These are a waste of money for multi-media use and should be calibrated with an accurate colorimeter (no Spyders) like the X-Rite Colormunki or i1 Display Pro (=cheapest good options) to maximize their potential.
Eizo CG277: Comes with a built in colorimeter, can be hardware calibrated, has colur compensation and is glow free.
Eizo CX271: Can be hardware calibrated, has colur compensation and is glow free.
HP Z27X: Can be hardware calibrated via XML editing*, is glow free and is better for gaming than the Eizos and NEC PA272W.
Semi-Glossy or grain free matte:
Dell UP2716DG: It can be hardware calibrated, but will not provide as accurate results as the others.
LG 27MB85Z-B: It can be hardware calibrated, is cheaper than the Viewsonic VP2772 and is delay free.
NEC PA272W: It can be hardware calibrated and has colour compensation.
Viewsonic VP2772: It has better colour presets than the LG which makes it more suitable for people who do not own a colorimeter.