Final Cut Pro cannot read the .mp4 files that one of my cameras spits out. My question is which is the best format to convert this video to before importing it into final cut pro?

I have visualhub and mpeg streamclip and have tried various settings. My source video is 720p, so I'd like to keep the size (it's actually going into a 1080 movie) and quality.

Converting to DV downscales the video, but is fairly quick.
Converting to xvid diminshes the quality, but is failry quick.
Converting to quicktime takes forever and produces enormous files.
Converting to mpeg2 or mpeg4 with h.264 works okay, but FCP has a hard time handling these files quickly (ie I can't even use the jog dial)

So which is it? What would you do?