My vote is for the 303. It does everything well and the same model is now strong enough for both CX riders and Tom Boonen to win the most brutal road races in the world. The 404 is only practical if you are doing long distance races on flat courses with a sprint finish. Not very likely to happen. I also prefer the symmetrical look of a 303 set vs the staggered 404/303 combo, but if you ignore looks the 303 is just the obvious choice for the OP's requirements. The hard question is going to be tubular vs clincher, but that usually depends on how much extra money and time one has to spare.
