RCI hands down. You don't own a Marriott or DVC to trade, so you will get left over availability after the preferred resort owners choose what they want with II. RCI has a lot more choices and a lot more availability for the average deposited week than II in my opinion. RCI has problems and I am mad as h*** that they rent out weeks we should be able to trade into, but they consistently provide me with a quality resort in the time frames I need to travel at my desired destination.
I leave Friday for a hard to get 2 bed room 2 bath Gatlinburg timeshare that I received from an RCI trade. Not only is it a big football game weekend (Ala-Tenn), but it is prime leaf season. For all of the complaining we all do, I have gotten virtually every trade I have asked for (as long as I am flexible on dates and the specific resort) except for Aruba through RCI.
Overall I like RCI and I won't quit until something better comes along. Should they be able to rent out our deposited weeks? NO!!! Is there an exchange company out there that has proven to work better for me than RCI? Sadly, once again no.