I actually play a lot of both and like them both for different reasons.
Here's what I would say though if I had to pick one.
If there could be something that limits how long archers or HA/HX could just run around and hide and dick off after 90% of each team is dead and just spectating or watching midget porn...
...Then I might pick battle. Otherwise, my pick would be siege.
I, like Penitent, work and have a lot of other things going on. I don't get on to "oh when you die just dick off and browse the internet", I don't really have that kind of time luxury to waste and thats what it feels like - a waste.
While battle with one life can be intense, it can also be infuriating especially since most of the time one team is just getting curbstomped because of the balancer. Believe it or not, I actually get into more good, 1v1(ish) duel type situations in siege.