I can't get down to one favorite guitar, but I'll tell you about my two favorite. The first would be my Green Jem.

Originally my personal website (www.greenjem.com) was used to track the first 777 green Ibanez Jem guitars. They are all signed and numbered by Steve Vai. Mine is #103 and also has "To Larry" written on the back from
Steve Vai. You'll see it has one of the very rare wrist rests on it that never actually shipped with the Jem because Kramer had a patent that it violated and wouldn't license to Ibanez.
The second is a guitar I built myself.

This one uses a Ibanez Saber neck and has a body that I built myself and electronics from a Saber. The body has two monkey grips instead of one, huge access cut away, the body is cut as thin as a Parker Fly, the front is signed (and scribbled on) by Joe
Satriani, the back is signed by Steve Vai and Joe Dispangi (the guy who invented the Jem line of guitars). Evolution pickup in the bridge. The paint job was done by Darren Michaels, a buddy of mine who did all the original swirl paint jobs on the Jem and Universe
guitars. This color scheme was eventually used in one of the G3 tours so the guitar matches very well with a couple of the posters from that tour that are also signed by everyone in G3. This one also has a Lo Pro Edge II tremelo and a rare wrist rest.
All of these and more hang in my office at home.