I feel like BM definitely has more going on in terms of having to make decisions, which in turn relates to me as "fun." SV had that going on with 12 sec trap but with it being nerfed, that takes away a lot of control. Not sure why people like to hate on BM, I think they're still thinking back to early Wrath beastcleave or something. As expansions continue there's a reduction in skill needed for SV and MM, while I don't think BM has gotten any easier, if anything more intricate. Most of the gimmicky things that people cried about regarding BM have been removed (trinket on BW, stampede, Core hounds, etc). When I watch high level hunters play BM, they still make a lot of micro mistakes with BM, that usually only happens with specs that have a lot of options, however there are hardly any mistakes that someone can make with SV/MM. In the grand scheme of things, WoD is relatively easier for every class. However this is not a thread saying what spec requires more skill etc.
Hopefully they continue to balance each of the specs and make each of them viable so everyone can play what they want, not what they have to in order to do well.