I voted for the 27" Dell Ultrasharp before, and i'll do it again.
Just a tad more expensive than the 24" version, for a lot better colour and more real-estate.
Half the price of the 30" version for an extra 160 pixels along the top and 99% vs 96% adobergb coverage. I'd get 2x 27"ers before i got one 30".
Double to triple the price of the 22" versions, you'd get more screen real-estae with the three smaller versions, but they're not as well calibrated or have as many options.
Just don't buy it now, if you can wait a month or two. Dell always have them on a 3-day sale, I looked first and it was $700, put it off and put it off, then the price rose to $800, put it off more, then the next week it was $540 on sale, I hit the 'buy' button before the page had finished loading.
Eizo especially are also good, but they're like Zeiss glass. Sure you'd probably get an extra 5% on performance, but you're paying for it. Dell are calibrated to <5 which is good enough for me, but you can buy an extra calibrator for less than an Eizo and get fairly similar results...