If you are comparing two things use better; much better; way much better. Or the best; the best of all, if you want to say that th are is nothing better than shorts for running. I hope this helps. Update: actually, you can say "pretty much the best" or something like this.

You certainly can; it doesn't sound grammatically correct but it is a phrase we use a lot. You could also say, 'by far the best' or 'comfortably the best'. I wouldn't agree with the other comment on this

Simply put: Tracksuits may be a bit warmer, but shorts are much better for running (in), whatever the weather. (You can omit "in" without changing the meaning.)