Depends on the occasion.
If I want to blow massive bucks, it's Prime at Foxwoods or Jordan's at Mohegan. Both steakhouses.
Taking it slightly down a notch, it's Alta Strada at Foxwoods or Tuscany at Mohegan. Both Italian.
For just chillin or eating at the bar it's Hard Rock at Foxwoods or Lansdowne at Mohegan.
I now avoid Cedar's at Foxwoods. Dated and too pricey for what it is, especially when you can go to Prime for almost the same price. Both casinos have good food options IMO. I haven't even listed others that I like, but these stick out the most. I STILL haven't been to TAO. On my list.