Had the most options.
I travely mostly for work (state govt employee). Although there isn't a Marriott hotel in every small Iowa town, they do hit most of the major ones, and they offer a competitive government rate. Some Hampton Inns are nearly double the reimbursement rate for us. Most of my stays are at FIs, and I find them pretty consistent as well. Some other programs have decent hotels, but you never know what you're going to get, one Comfort Inn might be nice, and I've had two Quality Inn stays that were terrible.
Love the MR program too. I have the MR Premier VISA program too, and enjoy the earnings I get from it.