Priest; they put out some decent (some might say great) albums with their revolving cast of characters behind the kit, but didn't break through until the legendary Les Binks got on board.
I don't agree with the premise that a "truly great" band (there's that term again, "truly great") must have a "great" drummer. However, I really don't agree with it as it relates to Priest. What's "legendary" about Les Binks? Prior to his tenure with Priest, he played on a few obscure albums. He's well-regarded for his work on Stained Class and Killing Machine/Hell Bent for Leather, but neither of those albums were real breakthroughs for the band. Without thinking about it too hard, I'm inclined to rank Sad Wings and Sin After Sin a little higher, but those four albums are all pretty similar in terms of quality and popularity (SAS had the best UK chart performance, while HBfL charted best in the U.S., and all but SWoD went gold in the U.S.).
British Steel was the real breakthrough album, and Priest was at its most popular during the Dave Holland era, and I don't think anyone would seriously argue that Dave Holland was even close to "great." Priest put out one great album after Holland left (an album which, in terms of drumming, was superior to anything Priest had previously done) but then mostly fell off the map.
Well, I'm not confusing (or defining) "great drummer" by "most technically proficient". I think both Ringo Starr and Phil Rudd are true greats in field, and yet Phil Rudd is likely the LEAST technically proficient drummer in his own band! Yet, the band is a different band with him than without him (and even Malcolm said that, and Malcolm - at least for a time - HATED Rudd).
I guess Lars is the exception to the rule here. It's not JUST a bazillion fills per second, or strict metronome timing; hell, John Bonham was not a metronome. He ebbed and flowed the tempo, but did so brilliantly, and in tandem with the rest of the band. I firmly believe that most covers of Zeppelin suck, for precisely that reason. They try to play it like it's to a click track, and that doesn't work for Zeppelin. Lars kind of is the exception on all points, I agree, and in my opinion, Metallica IS a great band, so...