I actually couldn't choose, because I see neither of them floating if you were to base their characters on their real personalities. Jooheon and Jackson are both tops. Bambam and Minhyuk are both bottoms. Bambam and and Taehyung would be a bottom and a top, but I feel their conversations would be more on the friends side, instead of the romantic side. For some reason I do like the idea of Jimin (as a bottom) and Jackson (as a top), but I foresee Jimin out-smarting Jackson and Jackson being awkward and getting hurt around Jimin.

If I were to pick a pair I'd still go with pair D (Jimin x Jackson), because they'd have a friction that would be interesting and dramatic enough. I feel things between BamBam and Taehyung would be too smooth and too nice. They'd rather be best friends instead. The other two pairings, in my opinion, would just be erhm... I dunno. Not an option? :P hehe.