I use Solaris (9 and 10) and RedHat (3 and 4) at work.

I use Ubuntu at home and love it. It has a great package manager and works "right out of the box".

I recommend Ubuntu if you want to use the laptop to get other things done. Other Linux flavors are easier to tweak/customize.

I don't have any experience with OSX, so I can't compare it with Ubuntu.