What was your degree you graduated in?
I would go with 4, finish what you started.
I do work with data mining and visualization on and off. I model humor in text and all that fun stuff. Finally getting a Masters after a few years of ups and downs.
I started 4 but got caught up by 1. 4 is ambitious and in early stages but I think I could throw together some proof of concept if I just looked at a small set of clear winners and losers.
1 is ready to move from a 'toy project' to analyzing real threads which will be the next hurdle. It was a project I did over a couple days and made a post about awhile back which most people here don't care about but I don't mind sharing.