I freakin' love Cait Sith and Nanaki! ^^
I don't like using Cait Sith in the Final Fantasy VII game, mainly because he's not good when it comes to physical attacks, which I'm a big fan of using.
And I ALWAYS over-used Nanaki. I just loved that pup so much, and after what happened to Bugenhagen, I almost started crying I felt so sorry for him <3.