What is more important?, mass or speed?
As far as I’ve gathered, speed = the extra damage your passive melee (or any melee) will do.
Mass though let’s you plow through, so you don’t hit hard and stop and be a sitting little duck.
Could be wrong.
Both are important - obviously you need some speed, but your damage is also greatly increased if you are carrying a lot of weight.
When Yokozuna came out I did some testing, and you can do an insane amount of damage ramming the impact meter if you can get it up to high speed with a lot of mass.