Part of the issue with Delta 3200 revolves around how much speed you really need, and how much shadow detail you're willing to give up to get it.
I like it at 6400 or even 12,500, XTOL 1:1, 75-80F (24-27C), 30 minutes, five inversions once every 5-7 minutes. BUT I'm shooting at night, where a few pools of inky blackness look O.K. Under non-night conditions I'd rate it at 3200 at the very most. XTOL gives as fine a grain as seems possible with this film. DD-X I've also heard highly recommended, but haven't had a chance to try it.
Another choice for high speed + small grain is TMY in XTOL, as above, about a stop slower than the Delta 3200.
If you WANT big grain (couldn't tell from your post), of course, I'd suggest Rodinal, although if you don't need the speed HP5 or Tri-X would give better defined, less "mushy" grain.