I slightly prefer Sony's approach as I don't like timed/paid for third part exclusives as they do not favour the individual consumer. I'd prefer to see each company take total responsibility for their exclusive content and most third party games to be exclusive unless the developer (like Insomniac or Epic with Gears) decide to focus on one platform for cost/quality reasons (which is of course their right).
Sony's approach may have higher costs however (depends on how much MS has to pay for exclusives of course) and it does perhaps lower chance for innovation as MS can spot independent talent and 'back it' for an exclusive - although Nintendo have shown this doesn't have to be the case.
MS approach leaves them slightly open to loss of exclusives or having the cost of exclusives soar as a 'hired' studio can easily decide to go multiplaform. As PS3 install base grows and developers see PS3 versions sell as well they will of course (unless stupid) demand ever increasing sums from MS to cover the lost revenue from PS3.
Both work as approaches though even though each has pros/cons.
Try to be reasonable... its easier than you think...
