Can't comment on the Canon, but have experience with the Sonys.
Have sent at least 3 of these models back to Sony for repair because of the built-in mics going bad over time. See problem mentioned in below thread:
http://dvinfo.net/conf/archive/index.php/t-16178.html
One repair lasted only a year, then went bad again. Repairs are not necessarily cheap. I've given up on these. Usually we use external mics anyway, but it is ridiculously limiting to have this problem -- what if you just want to grab a few shots outside, and you forget about this problem?
Apparently these mics had problems from the get-go, would deteriorate to the point where audio levels were very low or nonexistent.
If you go with one of these camcorders, at least always use headphones to monitor your sound (if using the built-in mic). Not a bad idea anyway (if possible), no matter which camcorder you use.
Good luck!