It can depend on the paper, post-development toning, and reflection density measurement, but for example using Ilford FB papers and my measurements, MGWT has the deepest max black, followed by Classic, followed by Cooltone. I recall also that in Richard Henry's book (reflection density measurements of a bunch of papers at the time), Agfa Portriga (another warm tone paper) had the deepest max black.
Note however as density increases, we are less and less able to discern differences. Perception can also change depending on cold, warm etc. So I would not make too much of small measured differences. Once you're at these d-max densities, all other things being equal you can't see the difference between say 2.1 and 2.15 so while it is relatively common for people to place a high importance on "max black", I would not choose a paper that way. They all get black enough.