Just get the biggest mah you can afford. I have some 5000 mah 2s SMC batteries (60c if I remember) in my VXL Stampede and it seems like it runs forever. Not an hour but a loooooong time. Swapping batteries isn't a big deal to me, it is not like it used to be where you would be lucky to get 5-10 minutes out of a pack.
I have not tried these yet but I know people who have and they work great. It's a solid company in SMC. If I ever get more Lipo packs, this is where I am going. The prices are great. People are using them in Clods on dual brushless so if they can pass that test, they can run about anything IMO