It depends on how much you want to spend- I honestly don't bother with speakers like Polk, Infinity, etc. The bottom line is you get what you pay for.
If you have the money I definitely recommend getting Dynaudio but you'll pay like 1500 for two-way components and about 2000 if not more for three-way components- if I remember the prices correctly. Focal's are really good to- very clean and you can drive them pretty hard without reaching distortion- I did a whole system install on them a few months ago and I really like what I heard.
Browse through Crutcfield's website and you'll find what people saying on all types of speaker brands- that might help you choosing as well.
-Sebastian
