Favorite Borderlands DLC?

The Secret Armory of General Knoxx.

The best one, by far (and pretty much the only one you need) is The Secret Armory of General Knoxx.

My personal favourite is the Claptrap one, though Knoxx adds extra leveling, so it has that advantage. If you already have them though, you get that extra leveling everywhere anyway.

I suggest starting with the Zombie DLC and leaving Knoxx and Claptrap for later. Ignore the other DLC unless you need the bank or want the bonus stat point from completing the arenas.

Secret Armory, hands down. Though I haven't played the most recent one yet (BL2)

my no1. The Secret Armory of General Knoxx and 2nd is zombie island

Secret Armory. Probably the best piece of DLC I ever got in any game.

Mad Moxxi's crapdome is the crappiest pointless...less piece of DLC ever :P