I have a couple of main standards and think that's a good idea, but I'm always trying other things, and once in a while I'll switch. I like TX and TXP for most things, in PMK for negs to be enlarged and ABC pyro for negs to be contact printed. If I want more speed, I develop in Acufine, usually for handheld 4x5" use. I would say these are my default choices for most uses.

Delta 400 Pro is a very attractive film in Perceptol at EI 200 and D-76 (1+1) at EI 400, but it doesn't come in sheet sizes. If it did, I might consider switching from Tri-X.

Efke 100 in PMK or ABC looks like it might become a second standard film for me, because it's available in 11x14, responds very well to pyro, is a little finer grained than Tri-X, and has an attractive tonality.

Then there are a few films I like for specific effects--

Ektapan in ABC pyro for Hollywood-style portraits, at least until I run out of 8x10", as it's been discontinued.

Fomapan T200 for a kind of Alvin Langdon Coburn/Fritz Lang look.

I don't do very much B&W in 35mm anymore, but if I want the grainy look, I've got a bunch of Double-X cine stock that works well for this.