Studying CS at small LAC or large research University before grad school?

Either program looks fine. There isn’t that much that distinguishes undergraduate CS programs from school to school, unless you’re on a specific track like games or security.

Graduate schools won’t care whether you’ve been on a specific track or taken graduate-level classes as an undergrad. And I always wince when someone worries about prestige and CS. Prestige is much less relevant in CS or Engineering than it would be for other fields.