Good eye, my friend. The writing's been on the wall for higher-end monitors for a while now, started noticing what a scam they are some 3-4 years ago but only a year or so made the plunge to a TV and oh how I wish I had made it sooner.
Check out rtings.com for some quasi in-depth reviews. What Legend is saying is mostly wrong. In fact, you can find 1440p 120hz Freesync TVs of extraordinary image quality (this year's Samsung QLEDs), but those are generally pricy (depending on how much you priorities HDR; lower models, e.g. Q6FN has worse HDR than Q9FN but way cheaper, otherwise close overall for the price difference). If you get a bit up to speed on TVs then you also have a chance to shop around and maybe find a deal on year's models, which are still superb (particularly the Sony XE930 & XE900) for a steal. Tbh unless you plan on becoming a pro gamer (on PC) then the input lag differences from a good TV to a monitor won't be very noticeable, especially if we exclude CS:GO. Otherwise 99.9% of games it feels great.
The Samsung sets you are correct on, although I have read numerous issues from people trying to run them at 1440p, but firmware updates may have fixed this. Plus, these are the ONLY range of TV's that have Freesync, so I'm not "mostly wrong"... HDR is still a joke on the VAST majority of TV's, barely meeting the required standards, with many falling pathetically short, and for the most part all will be 60Hz... and those few that have 120Hz panels will only do so with HDMI 2.0 at 1080p. That's just the facts. Oh, and don't even get me started on LG's RGBW shenanigans! Many consumers are completely in the dark on that one.
Input lag can be VERY noticeable to some people, while not at all to others. It's a very subjective thing, so it's false to issue such a sweeping statement as it "won't be very noticeable". Also, generally speaking, you won't find many people who switch from 60Hz to 144Hz that don't notice and appreciate that difference either. Of course it's a bigger deal in competitive shooters, but it's not a completely non-existent one in every other game.
Also, although OP acknowledges size is prohibitive for desktop use, it is worth re-iterating in respect to your points that we're talking about two different markets here with different use cases. The smallest Samsung is 55"... that's just not going to be suitable in place of a monitor for the vast majority of PC users. Don't get me wrong, they're great TV's, but it's clearly optimal and a very solid choice for a lounge/living room environment with an HTPC set-up or where you would connect your main PC for a different gaming experience. I'd probably choose one myself if I had that intention. But as OP asks, "size aside, are modern TVs better quality for games?"... the answer is no and yes, it depends on specifics. For pure image quality, undoubtedly... no PC monitor is going to be able to get anywhere close to OLED, but this is not necessarily the be all and end all, obviously... although for some people it might be.
Perhaps most importantly though, OP never mentioned his budget (assuming he's shopping around), which is a key factor in all of this.
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