I have a very love/hate relationship with Ubisoft.
I'm not a big fan of the Tom Clancy games. I used to love Assassin's Creed but it's lost it's luster. I've been watching my bf play Child of Light and it's really cute. I personally love the Rayman reboot. I miss Prince of Persia and need to actually play the Far Cry games before I pass judgment on them.
Overall, I feel that they are still a better company as a whole than EA or Activision but I wouldn't necessarily put them under the best of anything. As for 3rd parties, they are kind of up there after Square Enix (mostly for their Eidos franchises as of late though).
If you're talking about actual developers, they aren't even in the top 10. :/