I'd say not as important as GPA/DAT for getting an interview, but it gives you that extra bump. I mean, admissions are so competitive these days. Imagine someone with a 3.7o/3.9s like you with mediocre/alright LORs vs someone with say a 3.6o/3.8s with superb LORs. I think I might lean toward the one with great LORs. Assuming we control other factors such as extracurriculars, shadowing hours, DAT, etc.
For any class (small or large), you'll have to go to office hours even if you don't need help. This will give you one-on-one time with your professor, so
they can get to know
you better. No questions? Make them up. Or just ask questions about stuff you know the answers to, so when he talks about it and asks if you understand, you can go "Oh yeah, you mean this does that and that? Thanks doc! You're such a great teacher. I totally get it now."
Anecdotal, but an interviewer at my top choice also mentioned how I had such great LORs. Ended up getting in, so I might be biased when I say it's purrrty important...