When comparing 25 vs 27 inch, keep in mind that if they both are 1080p, then you are seeing the same number of pixels regardless of the size. You're better off getting a monitor with better color and contrast that actually looks nice, as opposed to deciding on size.
I've got a 27 inch at home, but it's 1440x2560, which is a glorious resolution, especially for desktop stuff. (Can get two full websites/documents side by side) I got mine for $300 on eBay from Korea, it's one of the B-grade panels that come out of the apple monitor factory. It's called the "X-star," there's a bunch of other cheap korean panels on eBay...