I had a couple of the X-Pod sets when I was little: 4339 Aqua Pod which had a cool shark, don't remember the other two models, and 4347 Auto Pod which had a little blue car and a cement mixer truck.
My favorite Creator set has to be the Green Grocer, though. I don't think the modular buildings were considered to be a part of Creator at this point, but whatever, they are now. I got the Green Grocer for Christmas when I was nine. I spent all day building it only to realize I had put everything one stud too far back so I had to start over. It was frustrating, but when it was finally done it looked great. I still have the set up on my shelf along with the Palace Cinema, Parisian Restaurant, and Pet Store buildings. The Green Grocer is a little worse for wear, as I've stolen many of the pieces off of it to use in other builds. The main shells and quite a bit of decor is still left though.
The set I really want right now is the Harley Davidson Fat Boy model that releases next month. It looks soooo cool, and the pistons move when the wheels spin and everything. I think it'll go nicely with the Caterham 620R that was LEGO Ideas set a few years ago. I hope the Fat Boys don't sell out before I get the chance to pick one up!
What's your favorite LEGO CREATOR set? Mine is the yellow Beach House from 2008! I had been dying to get it since it came out and FINALLY got it around 2010:D!
Well that's a toughie, but I'd say 6743 Street Speeder or 6745 Propeller Power.