Do you mean the sohc V6 vs the ohv v6 or v8?
ohv V6 - slow, reliable, just ok at towing, crappy trans, easy to modify.
sohc V6 - faster than ohv v6, still just an ok trans but at least 5 speeds, not mod friendly at all, lots of problems people are still having in other posts still. In a Sport it will haul pretty good.
ohv V8 - faster than either other engine, awsome low-end, a little winded in the high end, very mod friendly, awsome trans, excellant at towing.
As for gas mileage I guess its a toss up, theres a thread going around titled "GAS" or something like that, and just about all the ohv V6 and sohc V6 guys are getting the same or a lot worse mileage than the V8 guys. I drive our 00' 5.0 Mounty hard and get 15-16 in the city and 20-22 on highway.