Interesting. No hidden agenda here. Just looking to see everyone's goals. Actually, I'd rather not change one or the other. (I just hate losing anything, even if I gain -- which is why I hate gambling). But I'd go with more muscle. What can I say? I'm a vain motherfucker.
So the next question must be, are you training optimumly for your goals? I'll bet the strength guys do. But in order to build muscle, exercises must be made to be more difficult. The idea isn't to lift more weight, but to lift less weight and make it FEEL HEAVIER.
It's one thing to do dumbell curls with 60 pounds while swinging and dipping and all the things that are natural components of functional strength. But go on a steep incline and do slow concentrated curls with 30 pounds and it will actually be more difficult and IN TURN build more muscle.