I'm a druid main in raids. As for open world content, I'd probably say that base ranger or Soulbeast (PoF elite spec) are as worth running. Staff as a solo player is more or less useless at least IMHO. I've been running a shortbow druid a fair amount of time in open world content as a solo player and the biggest pro is, as Svennis said, the increased healing. Definitely a fun class to play, and if you're going for endgame content, it's the meta healer.