I'm still not comfortable at comparing points earning between the 2 companies, but here are some other thoughts...
I enjoy Starwood for the tremendous upgrades they give me, especially when on vacation. I buy the cheapest room and always end up with something much nicer, although not always a suite. Typically I pay for a cheapo garden view room and wind up with one of the nicest ocean view rooms. Ocassionally suites, sometimes even specialty suites that are not even supposed to be offered as an upgrade. I'm fairly new as a Diamond and still trying to figure out how the upgrade benefit works at Hyatt and how much I value it. So far I'm not overly impressed with Hyatt in this regard (but I do like the average room I get at Hyatts more than at many SPG properties I frequent).
Another positive I see with the SPG program is the conversion of SPG points to airline miles. If you transfer 20k points, you get a 5k bonus, for a total of 25k miles. If you move large amounts, these bonuses can add up (move 60k points, get 75k miles). My own preference for using miles/points is for international F tickets, which are normally upwards of $10k. Again, I'm new to Hyatt so I havent completely figured out how the "convert 50k points get 25k air miles" compares to SPG conversion.
Finally, SPG has cash and points, which I routinely use and find to be a good value. The few times I do cash in pure points awards, I think availability is great at SPG and can save you a bundle. I've cashed in 10k points for a $450 room at the Atlantic in Ft Lauderdale, it was a good value. Again, though I would rather keep the 10k points and build up the miles for an international F ticket, seems like a better value to me.
But Hyatt has FFN, which seems to be the deal of the century. Hyatt is getting all of my business for the next three months! SPG had a stay 3/5 get 1 free and a stay 10 get 2 free last year and I did well with that. Nothing of the sort from SPG this year and since I've already requalified for Plat, no need to put any business there.