I just finished reading Alan Moore's run on Swamp Thing, and I can
honestly say it's probably the best comic book run I have ever read.
Not only is the overall narrative good; some of the individual issues
(e.g. Loving the Alien) are outstanding standalone stories.  I read a
big hardcover reprint from DC Black Label, with updated colours and
enlargened, glossy paper.  The art and plot is outstanding, even by
modern standards.  Definitely recommended.  It's not at all as
simplistic as you'd think from the title and concept.

The original bronze age Swamp Thing run is also worth reading.  It
leans very heavily into classical horror tropes (the authors find very
contrived reasons to quickly visit both the Louisiana swamps, "the
Balkans", and the Scottish moors), but it was still much better than I
expected.