Both please. Luckily with my fiancee I got both though her brain is extremely specialized as a trial attorney but she is very smart, very cute and I'm quite happy with that arrangement.
Years ago, when I was a young and relatively stupid, I got somewhat involved with an amateur porn star who was, in all fairness, physically about as gorgeous as she could be and was about as sexually active as you might expect a woman in her line of work to be.
She was also...not dumb, just extremely instinctual? She literally could not make any relevant connection to existential thinking or complex concepts, when I'd talk about art or design or whatever else at the time I could just feel this gigantic vast emptiness behind her eyes when she'd just nod and "uh hmm" at what I was saying. She apparently fell in love with me because of...well because of sex to be as simple as possible, I apparently hit all the right buttons and she was "in love with me"....but she never really knew me or understood me beyond the physical because she just didn't have the ability to absorb and understand the very things that make me who I am...so again I won't call her dumb, she just...thought about life in a much different way than I did....so I'd say I would tend to lean more towards brain than beauty but if I can have both as I've been blessed with in my life, then I'll take it.
The porn star still contacts me on occasion, its been almost a decade now since I last saw her, and shes still in love, or so she says. I think her concept of love and mine are probably vastly different too.