I use a kryptonite evo mini. Super strong lock, I love it. I usually don't lock up my road bike anywhere (Raleigh Prestige full-carbon) But I would be comfortable using my krypto lock with it. I also have a cable that I use in conjunction with the lock.

I usually take my fixed gear bike out around town when I'm just riding around, I don't mind locking it up. Plus if it gets scratched up I don't care, I'll repaint it someday