That's a very difficult question to answer because everyone has a different preference in sound. Some people prefer a warmer sound, where others demand speakers that have a flat response. In my set-up I have a Jamo D6PEX7.1 THX system which I love since I only use it for movies, but if you were to want something for music it wouldn't be the best choice.
Like Robert said, its best to go audition several brands and lines until you find the combo that your ear likes the best!
I am using Infinity for the front 4 and subwoofer, Paradign for the center, the ones in the ceiling have floating heads but I do not know what brand they are because the ceiling is 16' high and I don't want to try getting up there to find out. My sound is great, theater-like. Very happy with it.
I use a series of b& w 683's main 600 cent 685 surrounds and def tech for front h and w. this amp has plenty of power and claims to support 4 ohm loads . But I think anything from kliptch , Polk, def tech and the like would be great . You should go unto some shops to listen . The on line emotiva brand grit a lot of good press . So many brands so many choices. You also might want to look up avs form there a lot of capable people there that can give you some great advice. Just try not to skimp too much on speakers good luck