Here's a review I found interesting about a 21.5" IPS made by Asus purchased in 2017. Those saying the monitor is irrelevant are off the mark in my opinion. She says:
I purchased this monitor in Feb 2016, it's now June 2017 (1 year 4 months). I must have ended up with a slightly different monitor than the other satisfied people who have purchased this ASUS monitor, because the monitor I received is terrible and it hurts my eyes. I tried to tough it out and only use it for a few hours or so every couple of days, typically wearing sunglasses because it's tough to look at this thing without eye protection, but I can't handle this monitor anymore. I have experienced more eye fatigue on this monitor than any other monitor or screen I've ever dealt with. I can't go more than 2 hours looking at this screen before my eyes hurt so bad that I have to stop using the computer. After a year and a half of this, I'm chucking this thing. I wish I had returned this monitor early on. I'm not sure if I can return it at this point 🙁
NOTE: A buyer who posted a really helpful review "Awesome but beware" sometime before Feb 2016 described that when buying this item, the buyer will receive their monitor from one of two manufacturers; one manufacturer makes the good one, the other makes the crappy one. I definitely got one of the crappy ones.
Someone else reviewing the same monitor says:
I think this product is very old now and it gave me eye strain before I finally got rid of it and bought a new monitor. I think the problem was that this monitor is not flicker free or something but my eyes couldn't stand looking at the monitor anymore after like two or three years of gaming usage. I recommend getting ASUS's eye care models, you don't want to go back to old technology and have eye stain.
I'm noticing Amazon carrying some older Asus models now that the newest versions are selling out too fast. I wonder where they're getting this old stock from. Anyway, like people have said, the exact same model can have a different panel inside, and you have no way of knowing until trying it out yourself. I'm also seeing older models now being updated with 75Hz panels, so those panels definitely aren't the same as the ones in older production units.
What I recommend is ordering a few at a time from Amazon and returning them for full refunds as needed. I'm also partial to lower end budget models because I think you get better value for your money, you have less money tied up in the monitor, and I suspect all consumer electronics these days are cheaply made and hit or miss. It's preferable to me having a few affordable units sent, trying them out, and sending them back as needed.
I have one coming in the mail now, but if I were to do it again I'd have 2-3 coming instead. The problem is I cancelled the other units I had ordered and now they're unavailable due to high demand. Amazon is very good about returns, so you shouldn't worry about having to box them up and send them back for refunds.
Also, in terms of screen real estate, you sure get a lot more value out of 2 24" units versus 1 32" unit. More screen real estate, lower cost, and modular in that you can easily replace one of the units should something go wrong.