Future slums of Wastegate still sprouting like weeds
Overall I find II to be a poor imitation of an exchange company but regardless of your opinion of II specifically at WVV they do very poorly. As Alan mentioned they get the majority of inventory from all Wastegates including WVV as the "preferred" exchange company of The Sleaze King. (Mostly because they grant his mostly rather mediocre resorts the highest awards despite the fact they don't deserve them. I mean does anyone think a Wastegate is equal to even the tiny DVC units or especially a Marriott level? Yet they get those rankings. And they do as The King asks no questions. Take a lesser value week for deposit that you don't own - II says "Sure! Why not"!)
While RCI sees only the limited amount from those Wastegates that were enrolled years ago it means the inventory is limited. Sometimes they even get a Silver Crown. (Although not recently as the maintenance / upgrades for existing Wastegates is sorely lacking. Hey, they aren't being sold so why would The King use any of the annual fees to do that mundane chore? They can concentrate on the garish new slum towers forever going up for sale and make money!) It has been a LONG time since any were at the Gold Crown level they once enjoyed (back when the 80's faux Italian look was still considered "in").
So the trade value with RCI does seem to be better as supply vs demand is a big part of that. Add in the superior choices and far more locations that RCI has over II and its not even a battle. RCI is the logical choice if you are stuck with a Wastegate ownership you wish to trade and are lucky enough to have RCI be able to take it.