EDIT MAY 22 2020 EDIT. Click on page 23 and 24 for the MAy 22 2020 update. All of the results are in.
Covid-19 lockdowns, i have plenty of time in my hands and there have been an influx of 240hz IPS monitors. So i took advantage of amazon's generous return policy and recycled my money over and over so i can try out MOST ips 240hz monitors. Keep in mind, i'm only comparing these AMONGST EACH OTHER. All of these panels in my opinion are exceptional and a good purchase if you think 144hz is giving too much motion blur(which is does). Lastly, this is in the context of competitive gaming and OVERALL. I put a heavy emphasis on "competitive gaming" since majority of people who purchase these monitors intend to use these for that reason only.
SS Tier
Tie between
#1MSI optix MAG251rx(#1 G2G, #1 colors(the only 10 bit IPS 240hz monitor, has backlight strobing at 240hz and below) it's also the best playstation 4/playstation 5/xbox one x/xbox series x) 240hz ips panel since it has VRR HDMI up to 240hz. Most importantly, you can keep your overdrive to "faster" and have little to no over shoot at MAJORITY OF ITS ADAPTIVE SYNC RANGE. 60hz-144hz(weird how hardware unboxed claimed overshoot at 144hz on "faster" when i myself didn't notice much if at at). Just put it to "faster" and you're set. OR put it to "fast" if uu dn't want to see any overshoot. (however, do NOT put it to "fast" if the framerate is 200+hz because the response time compliance would be too slow when its refreshing at 240hz at 4.17 ms)
cons
Backlight strobing is too dim to play and u cannot adjust the brightness. WTF, i was pissed when i found this out. But the crosstalk isn't as aggressive as elmb-sync so it is useable, u just have to tolerate the low brightness.
I dont know if this is anecdotal evidence but both of the MSI i've used has bad image retention. Either this is a panel variance or ALL of the MSI mag models have image retention(which may lead to burn in). Youc an easily test this by simply doign a ghosting test and after 10 mins, exit your internet explorer screen and yous ee those white dots(presuming of course you are using a black background).
Has the worst stand. No swivel no pivot. Just height(although its height adjustment is very good)
#1Asus TUF VG279qm/VG259qm(#1 MPRT at HIGH framerates ONLY, ELMB-SYNC is useful at high framerates which means the motion clarity and of ELMB-SYNC at 280hz overclock should be more sharp than any TN monitor right now. Strobe crosstalk isn't noticeable at very high framerates, and even if it was, the trade off is Motion clarity). This is the only IPS 240hz panel that can stand up to the TOP TNs. omen x25s or benq Zowies, or G sync predator TNs, AOC Agons, etc becauase 280hz is still 280hz, ELMB-SYNC is STILL ELMB sync. it's also future proofed because even if other future 240hz ips panels overclock their panels to 280hz, it won't have ELMB-SYNC.
The overshoot is more noticeable at 240hz than the Asus. I know this because in early transitions, i see blue halos. The trade off is a faster g2g response time. Feel free to click on my profile and see the topic i made of these measurements.
cons
response time compliance at 280hz overclock isn't up to snuff. Its response time is too slow to keep up with the refresh rate at 280hz which causes pixel smearing and ghosting ./ e. From what I heard, this causes more input lag. I've tested this and i havn't really noticed it but in the back of my head. ELMB-SYNC mitigates this issue.
ELMB-SYNC is useful above 200hz, nearly useless under 180hz framerates. Its locked at overdrive 80 which is in SYNC if the framerate is above 200hrz(although the crosstalk i s still too aggressive, mroeso than the MSI at 200hz, so you would need to try to go for 240hz and above. If you do, it's not as bad. Unfortunately, below 200hz, this monitor is very impractical for general adaptive sync gaming since the overdrive setting is more convuluted and confusing than MSI's 3 overdrive setting(just Put it on FASTER or "fast" if the FPS is under 200hz on the MSI and you're good).
S Tier
#2 [i]Viewsonic Elite XG270 [/i](will main the 25 inch version i f it ever gets released). In a practical sense, it has the best implementation of its backlight strobing for a wide variety of games at useable framerates(the adaptive sync range). This is the best 1st generation panel because backlight strobing mitigates the 1st generation weaker response time compliance for 240hz refresh rates*(4.17ms). Therefore you won't see much pixel smearing/ghosting compared to the other 1st generation 240hz IPS monitors if you use its backlight strobing mode. MPRT is very important in the competitive scene. and this is the best implementation of it overall. I have chosen this as my 2nd main. Without the stroving, at 240hz, it's indistinguishable from the MSI and the asus. 240hz is still 240hz. Those "UFO tests" isn't an indication of actual GAMING experience.
A tier
#3 Alienware AW2521HF. Same AU Optronics panel as the MSI optix MAG251rx and the Asus TUF VG279qm/VG259qm but why A tier?
-NO BACKLIGHT STROBING. Ever had one of those days where you are just playing horrible? Playing on tilt? and need a change of gameplay? what i usually do to break that cycle is to switch to motion blur reduction. That extra "SHARPNESS of fast moving objects" will REMOVE tilt and will sub consciously make you a more accurate player whether you are shooting the ball in rocket league or getting that perfect headshot on any FPS title. Welp, the alienware doesn't have backlight strobing. (at least for me).
-you have to turn on adaptive sync to make "extreme" overdrive useable, otherwise anything above the standard overdrive, you see ghosting. (THIS ADDS INPUT LAG). Esports or hardcore competitive players DO NOT USE ADAPTIVE SYNC BECAUSE OF INPUT LAG. At these ridiculously high framerates and high 240hz refresh rate monitor. Tearing isn't really noticeable and its freesync/gsync compatible VRR''s added input lag in MY opinion is NOT a good trade off in the context of high level gameplay at high framerates.
i don't know who the genius is who made this monitor but no backlight strobing and forcing adaptive sync? Does DELL not not know that at 240hz, these monitors are used for high level high framerate competitive gaming and not for casual use.
if however youa re using this monitor for NON competitive gaming, then i guess the 25" alienware IPS is just as good as the MSI or the 280hz Asus in that regard if not better. Maybe in the future, there is a firmware update where they reduce the input lag of FORCED adaptive sync? Even then, no backlight strobing is a major dealbreaker. . I ALWAYS STROBE as a way to break a bad losing streak and most of the time, it works for me. (then again, i only speak for myself when it comes to breaking bad losing streaks in competitive game, i'm sure others have other ways to deal with "losing streaks" but backlight strobing option is the one I personally use to break a bad streak).
PROS
Ergonomics are top notch. It's also the 2nd best looking monitor(it's beautiful, good quality and a good price). From my reserach has very good warrantee.
It's still just as fast as the ASus or the MSI( but forcing adaptive sync to avoid overshoot, if that is allowed then u might as well allow 100 overdrive setting on the ASUS vg279qm/vg259qm and enjoy its 0.8 g2g response time with massive overshoot. (just don't barf when you play fast paced games seeing blue artifacts/rings everywhere.
C tier
#4 Dell Alienware AW2520hf according to my research online(it's the fastest 1st generation IPS monitor, but the response time compliance is "barely" keeping up with the 240hz refereshing at 4.17ms). Although pixel smearing isn't that noticeable anyway at 240hz framerates. From what i've read, this really doesn't give you a true 240hz experience. I myself havn't tried this monitor but i'm fairly certain those sources are correct. This is one of the first ips 240hz monitors that have been released.
F minus tier(i skipped D tier, but i like the word "F" better than "d"
#5 Acer Nitro XF252Q s(i havn't tried this, but from what i heard, it's really not giving anyone a true 240hz experience due to the fact that the g2g nresponse time is too slow to keep up with the 240hz refresh rate of 4.17ms). i don't know how rtings is riding this monitor's nuts(excuse me for my vulgar slang).
Z tier($400 riding the coattails of its more successful 144hz nano cousin).
#6 LG 27gn750(no backlight strobing, no wide gamut nano panel although it has the best viewing angles, best color accuracy, and best color uniformity, and it's the best LOOKING 240hz ips monitor. If this had the NANO wide gamut, i would put this to SS tier. Nope, it's nothiing but a 240hz cash grab with barebones features. Still, it'sroughly just as fast as the 27gl850 and the xg270qg with less motion blur due to high 240hz refresh rate which adds better motion clarity to fast moving objects.