I think you’ll find that most of the liberal arts colleges have some sort of theater productions as an EC. Think about what you are looking for.
If you want a school with a strong major with an array of classes, and you want to major or minor in theater, then check out the great suggestions above. But if you just want to stay active in performing as an extra-curricular and you’re pretty sure you won’t take more than one or two theater classes, that’s a different story. You might find that you can get better parts in a less competitive program (although keep in mind that the productions might not be of the same quality).
I attended a LAC not known at all for theater, but our student led theater group was great. I got some good parts even though I was clearly not on the road to Broadway. Some of the productions were very well done, while some were of lesser quality, but it was all a lot of fun with wonderful people. Some students also got to write their own scripts and produce them, things like that. So be sure to think about your goals.