Who to ask for 3rd recommendation letter?

[fiveier.analysis]

I have had a decent amount of math courses but honestly having a hard time as to who to ask for recommendation letters. I don't really go to any of their office hours since I understood the material and did relatively well so I didn't see the point of doing so ... I did't like the idea of "schmoozing" up to them just for the sake of asking for their letters or connections down the road later, call me dogmatic ignorant or arrogant if you must, maybe I was a bit immature.

Anywho ... the 1st letter for me will come from my undergrad advisor. At my school each student is assigned a faculty advisor alongside a department secretary/advisor. I've talked to him numerous times for advice in applying to grad school, courses to take and what to do in summer, he also taught me advanced calculus and linear algebra. The 2nd letter will come from my thesis advisor who also taught me topology and algebraic topology. Our relation is relatively new since I only took topology last spring and algebraic topology this fall.

As to the 3rd letter I have couple choices, and they taught me different math courses but honestly nothing more than that. What should I do and how should go about choosing who to ask out of them?

[mathph]

This is what I would do because I'm in a similar predicament:

If more than 2 candidates for the third letter, pick the best 2; if only 2, submit both.