Diafine and Tri-X are a really good pairing if you need the extra speed. Rate this combination at EI 1250 to 1600 and there's not much that can beat it overall.
Second on the list would be HP5+. You can't get quite as much speed out of this combination, but it does quite well at EI 800. Don't expect "fine art" results from either of these combinations, but they work great for street shooting in low light.
FP4+ rated at EI 250 isn't too bad, though I really don't see the point. You get a better tonal response with Tri-X or HP5+ rated normally and developed in something like d-76 or XTOL. Naturally, there is a bit more grain with the faster films, but that's the price you pay.
Plus-X rated at EI 400 was a disaster the one and only time I used it. I don't think you can really get that much speed from this film in Diafine. Besides, this film is just so lovely in D-76 it's a shame to waste it in Diafine. I've never been tempted to use this combination again.
TMX rated at EI 160 gives you printable negatives. Other than that, I can't think of anything else good to say about the combination. There's no compelling reason to use this combination. It gives you a 2/3 stop speed increase with a lousy tonal range. This film gives better looking prints when pushed to EI 200 in something like XTOL.