The only exclusives you mentioned in that post are Gears of War and Halo 3. And I don't care how good Gears is, one game is never enough justification for buying a system. And the fact that you only mention MGS and FF as being reasons to buy a PS3 implies that you're either just ignoring the other great looking exclusives coming to the system, or just aren't that well informed on what the PS3 will have to offer.
Honestly, I'm going to just give the only advice that matters here: go to a site like IGN, Gamespot or what have you and start browsing the previews sections. Look at as many upcoming exclusive titles for each as you can to see what gets you giddy with anticipation and go with that system. We can recommend titles to look into but we can't tell you which is the better buy since you know what you like better than we do.