In HS, I only BM for Jarakus.
I really liked his voice acting. When you finally win after a long control match, and you also shout "O-O-OBLIVION!", it's twice as satisfying.
Added after 33 seconds
I don't like BMing, but often at the end of a match, if it was really interesting, I click "well played," regardless of whether I won or lost, and I don't perceive this as BM. Similarly, I click "amazing!" after particularly lucky moments for the opponent (and sometimes for myself).
Where do we end up when we save the world?