This is actually a very good question.
You honestly have to weigh up what you're after and what you're willing to compensate for.
--With a Korean monitor, you're receiving a higher quality display (in terms of eye-candy), unfortunately in comparison to a TN panel, your refresh rates are going to be slower (about 5/6ms (advertised)), vs TN panels going down to 1ms (advertised).
--You're also going to have to think about whether you will be getting your 120Hz at 2560x1440. That's a very high frame rate you're asking for, even on top of the range hardware. In terms of expense, can you afford to always have the top hardware in order to always maximise your monitor's frequency.
--Warranty. This is a biggie, buying from...