I just did a quick SPG vs HH. I don't know if I am completely off here as I did it in a rush. But I think the grass is not greener at starwood.
If I was going to do an HH vs. SPG comparison, I'd probably compare the 5-night awards or maybe the C&P awards on 1-night stays.
Also, once you get into Starwood Category 6 and 7, the value-per-point equation can go either direction (good or bad) in a hurry. If you've found a great Cat 6 with $350 rooms, consider paying for the room if you think it's worth it. Other Cat 6-7 hotels will have only $1,000 rooms, making the points look more attractive. Eventually you get into hotels you *probably* wouldn't actually book yourself with cash, so it's a bit like assessing the value you're getting out of a F/J award flight.
Whenever I do cross-program comparisons, I tend to use something like Starwood Cat 4 or 5 vs. HH Cat 6 or 7 vs. Marriott Cat 5 or 6. Although now HH has made this a bit more difficult...