ABS hands down, any situation, any road conditions, it's simply superior. A tire that is braking right at the point of lockup will stop faster than one that is completely stopped and skidding. It takes a lot of mental control to pull your foot off the brake pedal when trying to stop in an emergancy to get the tires turning again. Even if you are comfortable doing that, your physically limited in how fast you can pump that pedal, an ABS system can do it more often than you could ever hope to. Another advantage is most modern ABS systems are advanced enough to control individual wheels, pulsing each wheel at a different rate, something no human can control with just one pedal. This is useful on any surface that isn't completely flat and dry.

The reason you rarely see it on race cars is it isn't usually allowed. Most race series don't allow electronic aids like ABS or traction control. That is changing, I believe F1 has used traction control for a while and CART just started this year. Not sure though, I don't really follow either race series that closely. Some drivers that have spent their lives racing without ABS would also probably feel more comfortable without it. For a large majority of the rest of us, it's definaly an advange. Seeya.