I liked
Jonas before the
Jonas Brothers mainly because I'm a huge music nerd and love Weezer.
I do think it's a good name but, unfortunately, the association to the band kills it for me. As of right now and in the coming year, it's popularity may increase but I don't see it being anywhere near the top of "the most used names" list.
I prefer
Jonas over
Jonah. I'm not sure why, though, considering there's only a single letter difference between the two.