In my experience Delta 3200 has a lot smoother grain than T-Max 3200, and much better shadow detail than pushed HP5+ or Tri-X. The downside of Delta 3200 to me is the contrast seems wrong in some way I can't quite put my finger on. Basically the image will appear low contrast, but yet have clipped highlight and shadow detail, like a higher contrast film. To me T-Max 3200 also has more attractive and more natural looking grain, while Delta 3200s is quite a bit smaller/less but looks worse. I always go for T-Max 3200 when I need that kind of speed, or if I can do ISO 1600 then I prefer HP5+ pushed. At 3200 HP5+ loses too much shadow detail though
Edit: Also DD-X is my go-to for pushing film. HC110 dil B leaves too much "stray" grain in highlights and shadows to me and ends up with chunkier grain and less shadow detail. I've also used D-76 1+1 with good results, but I don't use it often enough to give much advice there. I've heard D-76 undiluted is great for pushing though, giving results similar to DD-X