For B&W I can also recommend HC-110 for old films. It gives a significant lower base fog. Comparing the same film (HP5+, 135-36) 12 y.o. in Xtol 1+0 and HC-110 dil. B, shot on E.I. 320:
Base fog Xtol: 0,40 logD
Base fog HC-110: 0,28 logD.
New film 0,2 logD although last time for PAN F+ the regular base fog is 0,25 logD which is IMO pretty high.

Clear Polyester films from Rollei, Efke and Foma (120, new versions) are much lower: 0,05 logD or even less. But here you have to watch out for the "light piping" effect, especially in 35mm.