If you build your system piece-by-piece, as I and many others here have done, just be careful to not take too long. Eventually speaker manufacturers replace models with newer ones. While the drivers may not change, the appearances of the cabinets surely do. I enjoy the visual appeal of speakers in addition to the sound they reproduce. While you want to get similar drivers from a single manufacturer for sonic continuity, you also undoubtedly want the speakers to match cosmetically as well. This is less of an issue buying online, because it's easier to find discontinued speaker models.

As for speakers, I own Polk Audio rti, csi, and fxi speakers. They have never left me wanting. I always look forward to listening to them. That said, there is always something better. That's way some people can't stop buying audio equipment. I also own a SVS PB10-isd subwoofer and absolutely love it. It has literally shaken pictures off the walls of the people living in the apartment above me, which embarrassed me a bit. I try to be a good neighbor.

Good luck building your system. Take your time and get what you really want, within some reason. If you buy junk you end up buying something twice.