Maybe I didn't put it in easy enough terms but you cannot just rev your engine higher to mystically make more horsepower. Again, by definition, horsepower is just a function of torque and like MrFatBooty alluded to, the best ways to increase torque are to increase breathing ability with improved heads, cams, or tuning or by increasing the engine's displacement.

As for what car will be quicker, that all depends. If I have two cars that weigh the same and one makes 150 ft lbs at 5000rpm and the second one makes 125ft lbs at 7000rpm you are wondering if the one making less power will be slower. The answer is no, not if you gear the car right for that engine. If the first car has a final drive ratio of 4.56, then multiply by the torque 150 and the tires are actually seeing 684ft-lbs which is what will accelerate the car. We change the gear for the higher revving car to a 6.37 keeping tire size constant and multiply by 125ft-lbs and the tires are seeing 796 ft-lbs which will accelerate the car quicker than the higher torque but taller geared car. So really it just depends on the whole setup. A little too simplified but that is how it works.