One of the reasons I use XTOL over D76 is that I find it a lot easier to mix up. You don't have to heat it up to 125 F or whatever it is. It mixes at room temperature.
While Chris gives good advice and has great photos, it's important not to take anyone's advice too much when it comes to film ratings. For the pictures Chris likes and the way he prints, meters, etc., 320 might be perfect for Tri-X. That doesn't mean that you won't decide to shoot it at 200, 250, 320, 400, 800, etc. It's important to do your own tests and figure out what you like. You don't need a densitometer etc. Just take a roll of film and shoot the same scene over and over with many different exposures (1/2 stop differences, whatever works for you). Then try to print/scan them all. Figure out which one gives YOU the picture YOU like the most, and that might be right amount of exposure for that kind of scene... FOR YOU.