I think Alex Krycek was the biggest prick as well as Spender (CSM)

my favorite bad guy was tooms...

Definately CSM, especially after the episode that was all about him...was it "Memoirs of a Cigarette Smoking Man"? I more or less remember the monologue he delivers when he sits down on that bench next to a homeless man who has just pulled a box of chocolates from the trash. "Life is like a box of chocolates, a meaningless perfunctory gift that no one ever asks for, unreturnable because all you could ever get in return would be another box of chocolates. Sure, there's the occasional peanutbutter cup or english toffee, but they're gone too fast. The taste if fleetng. Then all your left with is hardened jellies and teeth-shattering nuts. And if you're desperate enough to eat those, you're left with a box full of meaningless brown paper wrappings."