It's hard to say. The number of follow backs you get are not solely based on the niche. It has a lot to do also with account presentation. For instance, if you have a business account with a logo in the picture vs. a personable professional account with you in the picture, the personable account always wins. People are less inclined to follow businesses, especially ones they don't know.
On the flip side, an account with a person who updates their tweets more personably is more likely to follow you back, rather than a band or business.
So it somewhat ties into niche if you think of it as "who's automating and promoting themselves vs. who's tweeting just to tweet and be entertained". Regular tweeters follow back more often. Different Business niches? Not really. Unless they automate that too, which still doesn't matter. The Music niche? Not that much.
Also, "teamfollowback" or "follow4follow" people will convert into followers easier, and are rarely promoting anything. If your following because you have a product for musicians, don't bother, but if you're promoting music, they easily convert to fans in my experience!