What is the reasonable size of monitor for desktop application in home?
No one can decide what size screen is better suited to your needs than you.
Unless the 27" monitor is greater than 1080p (1920x1080) resolution then you won’t gain much from a 24" 1080p monitor.
I had a 27" 1920x1200, which gave a little extra screen space, less scrolling down. I have replaced that with a 24" 1920x1200, mainly because I couldn’t find a reasonable priced 27" 1920x1200 monitor.
Ideally I want to go to the next resolution up WQXD 2560x1440, so the real issue is what resolution do you want and then find a monitor size that gives it. You can get that resolution in a 27" or larger monitor. There are also 2560x1600 resolution monitors, but now you are talking expensive.
For me (and not just for me, quite a few of my colleagues had the same problem) 2560xsomething is too much on 27" - the letters are too tiny, your eyes hurt after a longer work, and subsequently your head hurts. (I’m talking about office / development tools, I assume it’s OK for watching movies ;)). Sure, you can set bigger fonts, but then some programs may start to look weird, when you connect to your machine via Remote Desktop, the letters are too big or tiny (don’t remember exactly which one)… I’d rather stick with ordinary 100% magnification.
I have 2560x1600 on 30", that’s fine - but for 27" I prefer 1920xsomething (I bought one 27" and I specifically went for those having 1920x, not 2560x).
As Craig said this is personal taste really. But I tend to agree with Igor in that I use a 27" screen with 1920 x 1200 in that anything larger starts to be too small on the screen for me