I feel for your situation. Having been top-tier in four different programs and on my own dime, it's nice having a choice of where to stay. However, as my nights started to drop I've had to do some sole-searching to decide which program(s) do the best for me.

Destinations became the major factor. Although SPG does not have a huge offering around the world, they do have properties where I spend most my time. And if there's not an SPG, there is usually a MI pretty close.

Program benefits were the next area I looked at. SPG just added a whole bunch of new benefits for higher night counts. Not that I expect to meet many of them, at least I feel they are trying. HH has hosed their program to the point there is no telling what you will find where and when. MR is missing the boat in providing actual benefits and just don't seem to care (i.e. latest Cash & Points - at rack rate only).

Customer Service was high on my list too. I don't expect any of the programs to be error free (although it would be nice) but it's how they handle issues when they come up that matters. CP misses that point all too often, so my saying is Choice is my LAST choice. SPG has been very good at addressing issues and having the active participation of the Lurkers on FT keeps them on top. MR has failed to deliver many times, both with providing a good web service and they have all but completely given up on FT in favor of their own in-house controlled (read censored) Insiders board.

Yes, the final decision is up to you. Deternine what you want and what you are willing to put up with and you will have your answer. Being able to leverage more than one program just adds to your options if you can swing it.