One way to size your trucks is to think about what you might get in the future, for decks. As an example, 8-8.5 decks, Id get an 8.25 truck. Plus/minus .25 works for most people as a ratio.
A simpler answer is, get an 8.25 truck. The 4 most popular brands are Indy, Venture, Thunder, Ace. All are good. I favor Venture and Ace.