Is bigger really better?

I asked my girlfriend to be completely honest with me and be real, and she said honestly it would probably feel better if it were a little bigger. Since she told me that I've been wondering how good she could have it with other dudes if they were like perfect at sex. I've had a thought in the back of my mind that it might even be fun to watch that happen...haha i couldn't tell her that though i don't think...so is bigger really better? not like huge, but def above average