We were just there and visited ESPN on two very busy nights. I do not think any one night is better than the others - but if there is a mjaor game happening on one night it will be busier than on other nights.
Also, there is no guarantee what game will be on the "main screen." But you can ask that smaller screens near you be changed to the game you are looking for.
If the line for dining room seating is long, try your luck in the bar area. There are high top tables and booths there, too. We waited for about 10 minutes both nights and were able to snag a seat, once at the bar and once at a high top.
Enjoy!