It's important to look at all factors when choosing studio monitors. Yes - the KRK's will definitely be a good choice, however, you do need to remember that the KRK's aren't exactly the flattest on the market. They do color the sound quite a bit, which will make your decision in whether or not to EQ an instrument, turn up the volume etc. etc. much harder. I recently got my first pair of studio monitors and I decided to go with the Yamaha HS8, which is the new series from Yamaha.
The Yamaha HS8 is much more flat than the KRK's in general (talking about the "Rokits", since I heard the VXT range should be much more flat and precise), however, flat doesn't exactly mean better. It's up to your personal preference whether you'd like a really sweet tight mix, or, if you would feel more joy by just producing and not caring much about mixdown, mastering and such. There is no right or wrong here, it's simply based on preference.
I'm glad that I went with Yamaha's, as I think I would have missed a big part of the mixing and mastering area if I had went with the KRK's instead. To me, the KRK's do seem to sound a little boxy, however other individuals might experience them in another way. Nowadays it's just very important that your overall sound design, mixing and EQing is perfect, therefore I chose to go with the Yammies.
Room size, acoustics and such things also play a huge part in which size monitors you should go with, aswell as which types. Go listen to a few different monitors in a music store - you'd get much more out of it by going that way, instead of buying something based on others opinions.
