It is purely subjective, I remember reading a post by someone over here who said that 27" was just right for him!! My sweet spot is 24" ... just get what you like. The 23" will have a better image though.
I had a look in a shop, and the 27" looked fine for Windows, but there was a 720 video on it, and even when i made it about 1/4 of the screen, it looked a little blocky to me. I was standing a *little* closer than the distance i sit, but not a lot (i didn't have a tape to measure). It was a pity they didn't have anything 1080 for me to see. I watch a little on the PC, but not a lot. General productivity use, the internet and gaming is what my block is for.
I know i'll be safer with ~23", but i would be annoyed if 27" would have been fine, and i didn't make that purchase first. My 19" has served me well, but i wish i got a 16:9 ~23 way back when.. though at a premium i suppose.
So torn
I'd love to use the 27" with Windows snapped left/right, but i could use my existing 19" as a second monitor with the 23". I use dual monitor at work, and it's ok - but i have zero experience using dual with a game running on the 'main' monitor with, e.g. Teamspeak/whatever else running on the secondary monitor.
I don't have the real estate to be able to run three monitors (2 for gaming just wouldn't work), so a big main monitor is my only choice.
I'm leaning toward
this one. Which is about AU$110 cheaper than the 27". Maybe i just need to wait until they make 27" at the higher resolutions, and then wait for the price to drop - that'll be another couple of years at least. And this 19" 4:3 Samsung has been really nice to be for a good 5 years.
Man, 3x23" would be so awesome
But with literally 1.2m of width, it will never fit.