Good Morning,
Decades ago, I used Kodabrome II RC, Grade 2 for all contact sheets. When that became unavailable, I changed to Ilford MGIV RC (no filter) in 8½ × 11 size. I chose the larger size because arranging negatives on the paper is a bit less fussy and because it gives a little more leeway with 6 × 7 negatives.
I've always been careful to aim for consistency on contact sheets: same enlarger height; same paper; same lens; same f-stop; same exposure time, etc. Consistency makes it easier to diagnose potential problems, such as a shutter or diaphragm which is misbehaving, a possible development anomaly, or a new film/developer combination..
Since I also record printing data on the back of contact sheets, little printing exposure guess-work is required with new negatives of similar size. Contact sheets are easily filed, and the boring time spent on them is well worthwhile.
Konical