very subjective topic :)
Right now I'd have to say the Panasonic camp (HVX200, HPX170, HMC150) and the Sony Camp (EX1) are the big dogs in the +/- $5500 range (with the exception of the HMC being $3500 ish).
I wouldn't say the EX1 is the "most powerful" of the bunch, but it is clearly the sharpest camera. Panasonic's HVX200a, HPX170, and HMC150 offer what people generally agree upon as a more "cinematic look" straight out of the camera. However a lot can be done in post to achieve similar looks with the EX1.
Another thing to consider is the video codecs each use and how this will effect your editing. In short, the HVX200 / HPX170 shoots in DVCPRO and that is without a doubt the most robust editing codec of all the cameras mentioned, and easiest to edit.
You really can't go wrong with any of these cameras and I would research all 4 of them and choose the one that best fits the shooting you will be doing. The HMC150 is the newest of the bunch so there is not as much collective information about that camera as there is with the EX1/HVX/HPX170.
However if you can wait a year, there are so many exciting things on the horizon happening in HD. I am personally most excited about how dSLRs like the Nikon D90 and Canon's 5DII are affecting the HD market. It is no secret that Red has admitted the release of these cameras had at least something to do with their decision do a major overhaul with Scarlet. THAT'S exciting! It's just a very exciting time for HD.
