Tuscany, by far.
1. They have three days with 10x points, Wednesday, Friday & Saturday. The 10x points adds 1% to the payback, making games like 8/5 BP and 9/7 DB playable. Multi-line games are not eligible for the 10x points.
2. In February, they have gift cards on Tuesdays. 1,000 points = $10 card, 5 cards max. Since each dollar in earns one point, this is also a 1% addition. And you can play the multi-line games, reducing the time needed to earn the 5,000 points.
3. In addition to the cashback, you also earn comp dollars, which you can use in the restaurants and gift shop and for the hotel. If I remember the numbers correctly, this adds another .5% or so to the payback. The Gift Shop will special order for you if their vendors have something they don't normally carry. I regularly order boxes of cigars.
4. Restaurants - there are three and one snack bar by the pool. Coffee Shop has some pretty good daily specials, for example steak and eggs for $6.99. The Italian restaurant, Tuscany Gardens is surprisingly good. In the morning, at the pool snack bar, they large breakfast sandwiches for $2.99 (I think...its either $2.99 or $3.99).
5. Clientele - fewer wierdos at the Tuscany.
6. Slot Club desk - really nice folks working there.