It really depends on what type of sound you prefer andwhat your primary usage will be. For multichannel music, I'd recommend going with a direct-radiating type speaker for its accuracy and placement. For a primarily HT system, I'd suggest a dipole/bipole design for the diffuse surround effect. FWIW, I'm using Paradigm dipoles in a mostly 2-channel music setup, but they do an excellent job with HT and I'm very happy with their multichannel performance. I prefer the wider diffused sound of the dipoles over monopoles. Again, it's a matter of which sound you like and what you'll be using them for. If you haven't heard dipoles/bipoles, I'd suggest giving them a listen.
Jason