We use Hakko 951s at work, they're GREAT irons. I also personally own a JBC CD-1BC which I use at work.
If I had to pick a favorite, it'd be my JBC. It's easier to swap tips, easier to control temperature, and the sleep/hibernate features are easier to use and work better. As for thermal capacity, there's not much between them. The JBC may have a slight edge, but they're both very capable irons.
EDIT: I should also mention that I haven't used a wide tip on the JBC yet, but the 0.6" hakko tip works great. I didn't have to turn up the temperature at all.