Xtabi would definitely be my choice, it is still one of my favorites and I have stayed there several times. We even go there multiple times each trip when we are staying somewhere else. Rooms are great value, food is great, drinks great, awesome view, etc.
I have also stayed at NBCC and the beach there is very nice, restaurant is also nice, rooms are ok

I have never stayed at Oasis so cannot comment

But my choice would be Xtabi hands down
3 dives is right next door, there are lots of places nearby for food in walking distance and a grocery not too far down the road