The Wolf Man edges out Frankenstein for me--largely on the basis of the superb score. It masterfully controls the mood of the entire film. Of the films listed here I'd rank The Invisible Man third. But the top 6 of these films are close in quality. I'd put The Mummy and the 1943 Phantom substantially below the rest.
Pacing is a huge strength of The Wolf Man. It consistently moves forward, builds to a thrilling finish, and wastes no frames. And the final hunt sequence is bravura film-making all-around. The score, editing, and cinematography combine in the same way they do in the climax of the original King Kong.
Aside from the lack of a musical score, Frankenstein is pretty close to perfect too. Too bad that Frederick Kerr's terrible work as Baron Frankenstein brings several sequences to a dead stop.
I can see this poll was designed around the Blu-ray box. But I think The Black Cat should be a choice here too. It's a truly sensational film.
P.S. Chaney's Phantom was indeed a Universal film CPT HOOK. Unfortunately they forgot to renew the copyright--which is why the rights are muddled (and why the Rains version finds its way into the Universal box sets).