For the Tri-X, I'd go for Arista Premium 400 for $2.19 per roll for 36 exp. At that price for new film, expired Tri-X is hardly worth it. This is especially true with faster films that do not keep as well as slower ones.
For color, Fuji Superia Press is my recommendation. I am particularly partial to the X-Tra 800 at $3 a roll for 36 exp.
Sometimes you can get the amateur version of Superia in 24 exp. rolls at places like Wal-Mart for very good prices. It is the same film as the Press, which is a professional film, but has a slightly different color balance to offset the effects of the relatively slow use and unrefrigerated storage that is expected of "consumers". Like I said, same film, though.
This is assuming 35mm, of course.