"A liberal is a man too broadminded to take his own side in a quarrel." - Robert Frost
I kinda like it, as a critique of what's wrong with liberals.
My favorite anti-conservative quote comes from a semi-famous comedian:
"A liberal is a guy who wakes up in the morning and says "I feel great, but I know that some people don't" A conservative is a guy who wakes up in the morning and says "I feel great AND THAT'S ALL THAT FUCKING MATTERS." -Marc Maron