sdsearch has some great thoughts. I'll just add to that by saying that to me Choice points are good for road trip type stays and Marriott points are good for staying in the same place. Choice has some great value redemptions, I think they often give a better value than Marriott, but the quality isn't as consistent as it is for Marriott.

Its also worth mentioning that the current choice website makes it extremely difficult or impossible for many people, me included, to book hotels using points. Hopefully they fix it soon, but for now its something to keep in mind.

I like sdsearch's idea to have a few of both. That way you can tour around, with 1 night stays in Choice hotels around the country, and then stay for 2-3 nights at a Marriott in a city you want to experience.