IMO....Slash is a slash, doesnt really matter what size you get it will be about the same. Question is would you rather jump larger obstacles and race, or are you just looking for something little and fast you can street bash or hit smaller jumps with?
I personally would pick the 1/10 over the 1/16. They both have about the same parts support and just as durable, but no one I know owns one and trying to keep up with others when I'm racing/bashing would be a pain with a smaller scale. Just like any woman will tell you "BIGGER IS BETTER".....lol