Tri-X as my standard film. I know it "by heart" having shot it since it was rated at 200ASA and considered a radical film by the press shooters! "200 ASA, thats impossible, grain must be HUGE". It is not a perfect film, but it will always give you a neg with something on it! I have pulled and pushed it more than taffy at a fair! As slow as 6 ASA and as fast as 6400, not pretty but it worked.
I suspect that the world is divided into two groups of people, Tri X shooters and HP5 shooters. Religion, color, creed, politics we can always find a middle ground. With the Tri X versus HP5 - not a chance!
An other favourite of mine is Kodak's movie stock Double XX. Rates 250 ASA in daylight and 200 in tungsten. It is the same old style emulsion as movies like "Casablanca", The Third man, and I suspect that George Clooney used it for "The Good German". As it is a movie stock it is biased towards the mid tones and if you use a developer like D-76 or D-96 (Kodaks developer for this film) you get nice tonality and still retains high light separation. Comes in 400ft/1000ft or even 3000ft cans!
I do use other films, but Tri X is always at hand.