Studio monitors are tough, some people use regular speakers like computer monitors, but unfortunately they color the sound way too much, and you end up with a mix that works great for that particular type of speaker, but not for all speakers in general. Yamaha was very famous for their white coned studio monitors because they sounded awful, so if you were able to get a good mix on those you would have an amazing mix on almost everything else. That being said, I've always been a big Dynaudio, and believe it or not, Presonus makes some outstanding gear too. Genelec is the most used I believe.