The Aeroflow is a very functional piece, but the quality control on the 70mm TMD fans they use is pretty poor. If you get a good fan it's a great deal, if not, you don't have huge options.
The SP94 is a work of art. Even my mother was floored at the obvious quality and engineering present, it truly is a work of modern art. My mother is 62, and no PC freak (although a heavy PC user). I had never seen her show an interest in PC hardware before, beyond what it could do for her. We handled and discussed the SP94 for about an hour, praising its magnificence.
In addition to being a divine piece of techno-art, the SP94 is the best P4 heatsink currently available. Its mounting is awesome, it's worth pulling the motherboard and removing the stock plastic tree to mount it. And it gives you the choice of all the 80 and 92mm fans on the market. I've only tried 10 or 12 on mine. With a loud fan the SP94 is clearly better than any other heatsink going, and loses less of its cooling power with a quiet fan than any unit but the Zalman 7000. If you see the PC as a hobby your money is rarely better spent than when you purchase a SP94.