I half-suspect that a certain controversial pastor in Seattle would like Brawn. Brawn may be small, but there's no disputing that he's a tough guy, and if you want to question it, Brawn will be happy to prove his point by punching you in the face (especially if you're a Decepticon). No other Autobot plays up the "macho" image more.
Personally, I think he's overcompensating.
It's not that he isn't actually strong. He's second only to Optimus Prime in this department among the original line of Autobot characters. Rather, it's that he seems to have such a deep need to prove how strong he is. Rather than just going up to a wall that needs demolishing and knocking it down, Brawn will first tell you how badly he's going to tear down the wall, and how pathetic the wall is compared to his ability to destroy it. Compare this behavior to, say, Omega Supreme (a character from the following year, and indisputably stronger than Brawn), who probably wouldn't bother saying anything, and if he did, his response would probably be two or three words at most.
But, despite this personality flaw, Brawn remains a good guy at heart. He doesn't just punch people out unprovoked, and usually uses his demolition skills to help his friends and fellow soldiers. He just has a bit of a temper, and may take a minute to remember who's side you're on if you just called him a wimp. So if you like your face in the arrangement it's already in, take my advice:
Don't call him a wimp.