depends....
pleasure hunting i would rather him be fast on track, i can track him on a system. plus the faster he tracks the more drops i can get in a night.
comp hunting i would like more tree power. when getting your pluses you will need to be able to hear him over the rest so i would like him really really loud. in the same breath though if you are comp hunting you want to get to the tree first so you can get the most points.
it's a quagmire. i personally can tolerate a fast tracker with a smaller voice than a slow tracker with a big voice...from what i've seen of my boy so far he is a pretty fast tracker with a big voice...lucky me...