Favorite GURPS book?

There are so many GURPS games out there, that I don't know where to begin...

Any recommendations? Is Bunnies and Burrows any good? Ever since reading Watership Down I've been contemplating running a game.

Personally, I'd say GURPS Places of Mystery, but that's probably because Steve Jackson gave a signed copy to me after I had been his liaison at GothCon XX (a gaming convention in Sweden 1996).

GURPS Steampunk, GURPS Steamtech, and GURPS Castle Falkenstein top my list. The rules for anachronistic mecha in GURPS Mecha make me happy, too.

If you are running a game in which your characters are supposed to be rabbits I guess Bunnies and Burrows is your only choice, but I have no idea if it is anywhere close to Watership Down. I have never looked very closely at any of the specific setting books, although I have played a campaign in GURPS Wild Cards, and that books stays quite true to the original setting. Aces Abroad is an okay adventure for the setting too, although it is quite high-powered.