Three column template versus web2.0 theme and two column blogs

I have been clinging to the current theme for more than 6 months by now.
Sometimes I think of changing the style once in a while.
In the beginning, I used to change a lot of style. Whenever I got free time, I would sit and kill the current theme and then look out for new ones. But the problems would be regarding the speed and look.

I have seen pretty much every kind of design my now: while blog hopping.
I am thinking ...
Which one is the best....
Three column template or web2.0 theme or two column themes?
I can say that I do not like two column themes.
So, it really comes down to three column themes versus web 2.o themes.
(well, wordpress based themes are really awesome too)