the 3rd is my clear favourite. I like the scherzos and slow movements of 2 and 3 to about the same degree, but for me the 1st movt of the 3rd is more beautiful than that of the 2nd. (though admittedly its development sucks a bit). The 2nd subject in the 1st movt of the 3rd is IMO one of Chopin's best cantilena melodies, which is saying a lot. Like other people above, I never understood what the point of the 4th movement of the 2nd was, whereas the finale of no. 3 has more teeth and beauty to it.
The 1st doesn't do it for me, though I don't know if it sux as much as most people (including Chopin) say.