I spend most of my time in Unions South, Wendt, and Engineering Hall. I like those three because they all offer a slightly different environment and are very close together so if one is full I still have options.
It depends on the time of day and the amount of work. If I’m not swamped and I might be a little hungry, I really like the Sett or just Union South in general. When I have a lot of work Memorial Library is my go to.