You're right about the speed thing. I've heard that claim before and I just don't see it. If anything, FF seems faster to me (at least on the sites I surf) because it doesn't reload cached files as overzealously as chrome seems to. Chrome also seems to "hang" on connecting to some sites for me. Obviously Chrome launches faster, but I usually have a browser open most of the day anyway, so except on lower-end hardware I just don't see this as a big selling point.
Like you said, personal preference. Neither browser really has anything that the other doesn't, or won't soon have. Firefox has a lead on that, but once an official version of Chrome with easy extensions is out for a while and their community extension support picks up, it really will be a wash for the most part.