I have a few of the Roy Thomas/Gil Kane WARLOCK issues, and I agree. Roy Thomas in general was an acquired taste for me, as his dialogue in those days definitely leaned toward stilted and overly-Shakespearian melodrama. I think it worked best in CONAN, but turned me off in other titles like THOR and WARLOCK.
I actually hadn't realized that WARLOCK had been cancelled, and then was revived several years later when Starlin took over the series in STRANGE TALES 178-181, and then in a revived WARLOCK with issue 9.
I'd agree that WARLOCK is Starlin's best work, not only for sporting his best art, but also for the level of closure the series had. CAPTAIN MARVEL (and the later DEATH OF graphic novel) were good but he was still developing when it began, and is a bit more open-ended.
DREADSTAR, while I love the painted art and sophisticated story in EPIC ILLUSTRATED 1-9 and the two painted graphic novels, is diminished by the later DREADSTAR ongoing series, that declined with issue 6, that ceased at some point to be an epic sci-fi series and devolved into just another episodic superhero series.
It could be said that DREADSTAR was destroyed by its own longevity and success.
I have Starlin's WARLOCK series in its original issues, and also in the 1982 6-issue WARLOCK SPECIAL EDITION reprint series, and at one time had the FANTASY MASTERPIECES (1980-1981) reprint series, so with all those already, I never got around to buying the Marvel Masterworks hardcover. But it is infinitely worthy of the hardcover treatment.
