Definitely there are a number of threads out there comparing various programs. Here are a few:

Is Starwood Slipping? Or Are Others Catching Up?
Hilton HHonors versus Starwood Preferred Guest
Thinking about switching to SPG

There are others as well, you might want to do some searching in the various hotel forums themselves.

Overall, the answer to your question depends on a number of factors though. Where are you travelling? How many nights per year? What type of hotel (inexpensive, moderate, full service, luxery) will you be able to stay? What will be your travel patterns (i.e. one place for long stays, many places short stays, etc?) Where/how would you want to use the points you are aquiring?

Each of the hotel chain programs have their strengths and weaknesses. Your job is to try and figure out which chain's strengths match up with your travel and redemptions needs. We can help, but we will need to know quite a bit more about you and your situation to do that.

Good luck in your journey.