I have an HP LP2475W and a Dell U2412M; generally, among the IPS class, the consensus seems to be that HPs have more outputs and a better UI. Some of them are wide-gamut, however, which turns off a few purchasers. Research as to whether or not wide-gamut is important/detrimental to you.

I'd say go for 24s or a 30; if you have the 27 you'll just wish you had the 30 :-p but definitely go IPS, they are fantastic. I haven't read much about the Korean monitors as they were nonexistent when I researched the market 4-5 years ago.