A point to note is that with the 15 nights from the Marriott Premier Visa card and 35 nights, you will have Marriott Gold level (not stays, but nights). If you stay somewhere for a week at a time, then a program that maximizes nights might be better. If you stay only a night at time, then a program that focuses on stays might work to your advantage. One of the strengths of Marriott's program is that their Gold elite level is actually a decent level to attain. At FS Marriotts, you will get access to the CL (assuming there is one) or breakfast during the week, room upgrades (not normally suite upgrades, but I have received those at about the same rate as when I was a Plat), room type guarantee, etc.

One more thing to think on is what awards do you want? Personally, if I were looking at picking a program to start with, I would look at my stay patterns (approx 30 nights/yr @ $300/night) plus add in CC bonuses and any other bonuses you think you might be able to attain. You now have a rough idea on how many points you will acrue in a year. Now look at the awards for each program and decide which one is more likely to have attainable awards that you want.