I guess if I were to list the ones I use the most it would be XTOL for all film formats and HC110 for some LF applications. I have pretty much standardized on using Delta 100 and Trix for 35mm and the XTOL produces great tonal range, and as Thomas pointed out, it has great flexibility with dillutions. Of course there is the occasional TriX or HP5 in Rodinal and I am moving more towards PMK for sheet films.
I use Pyrocat-HD a lot, but voted for "other". I use the Pyrocat-HD mostly for 5x7" and some 4x5", and Beutler's for smaller sizes which won't be contact printed. Unless the contrast range is extreme, in which case I'll use Maxim Muir's compensating Pyrocatechin - or divided D23.