I had to vote for PS3, but purely from a hardware standpoint. It has superior hardware especially for the price. However, no console can touch a high end gaming PC. BUT...you will pay out the ass for one of those! Plus there is constant upgrades to keep them current. To much money and a pain in the ass.
So it would really boil down to PS3 vs 360. They've both got problems, but PS3 wins in my book just for the hardware and what the PS3 will show its capable of in a few years once the developers figure it out. Both are equal right now in terms of the games they've got. Give it a few more years and I bet the games out now for both systems will look like shit, once the developers figure out what they can actually get away with on both systems. However when this generation of consoles is done...I predict the PS3 will be crowned king!
I've only got the 360, and I love it! But I wouldn't go so far as to say its the best system.