In my "honest" playthrough I did not recruit 'Bull at all, actually. I did not like the idea of having a guy in my Inquisition leaking information even if I knew about it; I prefer to play things very close to the chest, and can quite easily pass up on a potential companion solely to promote the culture I want. I think this DLC aptly showed why that is important. Even recruiting him with the "Don't make me regret it" dialogue option does not work for me because spies have all sorts of codes that are not easily detectable and can pass security-checks.
When I do recruit him, though, I typically go for the alliance for a host of reasons. One of those reasons being: if I do not trust allying with those Qunari, then I really should not have recruited this one, either.
I like Bull well enough. He is far from any favorite of mine, but I got along with him fine and did not have any issue with him. When it comes down to it, though, I find myself preferring his betrayal to the alternative because... his character is not very memorable at all, otherwise.