I had an olympus, picture quality was poor, movie mode not too good although apparently better on the newer one coming out.
Now have the panasonic, picture quality is up there with all but the best compacts, movie mode is great.
played with the pentax but the controls were horrible
Canon has a sticky out lens so isn't compact, but takes great pictures.
There are a whole bunch of new waterproofs coming out, sony and casio ones look interesting, think the sony uses their new fancy cmos sensor thing.