I don’t have a single favorite, but generally it’s going to go something like:

Triangle.

The Void.

The Endless.

Moon.

Upgrade.

Delicatessen

Have you seen Vivarium or Color Out of Space?

I haven’t seen Vivarium, although it looked like it would be good. My wife loved it.

I enjoyed The Color Out of Space for what it was; Dagon was another pretty solid Lovecraft adaptation. Oh, and for older horror, there’s The Re-Animator, and From Beyond. I think a lot of Lovecraft doesn’t translate to film very well; cosmic horror as a fiction genre just isn’t quite the same as cosmic horror in film. Adaptations of books and stories to screen always have to make compromises that can cost some of the punch, and showing something–like the screaming bear in Annihilation–can give you more punch than trying to set the same scene up in a book. Neither is ‘better’ than the other, they’re just different art forms.

If you’re into these movies, I’d recommend Necronomicon, a 1994 anthology Lovecraft horror film. It’s been out of print, but that link will take you to the full movie hosted on archive.org

It’s weird and interesting