My favorite high speed film is Neopan 1600. It has much finer gain than TMZ or Delta 3200 and has a really nice look to it. In the last year or so, it's been almost the only 35mm film I use.
It isn't as fast as the others. It looks good at 800 or maybe 1000. It probably useable at 1600, but beyond that I'd use TMZ and even at 1600 it's a tossup, shadow detail or finer grain. I find the flat highlights of Delta 3200 to make it look dull and lifeless in most situations.
On the other hand, I shoot more 120 film than 35mm. In 120, the only choice is Delta 3200. I get an honest 640 out of Tri-x in Microphen, but for real high speed Delta 3200 is the only choice. I'd probably use Delta 3200 much more if the highlights didn't mush out. I really wish Neopan 1600 was available in 120, I'd rarely use anything else for handheld medium format work.