For snow, the savage stock tires work best for me. For bashing in the dirt, I use the imex swamp dawgs (medium compound) or the stock savage tires... depends on how much jumping and not landing on a downgrade as to which tires I run in that case. The imex tires have soft sidewalls and get cuts in them from the rims upon impact. If your jumping onto a downgrade, the impact is less, so it's not as rough on the sidewalls.
But for general bashing, I like the savage tires the best.
I've run Imex j-hawgs (medium), but they were so hard that it wouldn't hook up on anything, including concrete.
Pro-line mashers and they just spin all the time. Pro-Line road rage were ok, but the tires walk on the foam from side to side pretty bad.
Imex swamp dawgs hook up good on pavement, loose dirt/gravel and grass, but you have to be careful of the sidewalls on big air. Lightest of all I ran. (9 oz per tire/stock maxx rim)
Savage stock tires seem to hook up on just about every surface I run, but they are a high sidewall tire and you get a lot of tire roll to the sides when cornering.
Traxxas stock maxx tires are ok on grass and concrete, but sucked ass on dirt/gravel. Lots of spinning and loss of control at high speeds. Also, they are the heaviest of all the ones I've ran. (14 oz per tire/stock maxx rim)