My favorite is a 30" 2560x1600. The vertical pixel count is very nice. The Koreans can deliver these at a reasonable price. If you have money you can get them for about 1K in a nice IPS flavor.
I don't like the 27" 2560's because the dot pitch is marginal for my below average eyesight.
And I have yet to find a 1920 x 1200 27".
Right now I am using a cheap pair of 27" 1920 x 1080, but I am definitely going to at least one 30" 2560x1600 in the next couple of months.