Another possibility (although so far as I know, not considered by the editors at DC) was Alex Nino. Nino has a wild linestyle that would have been a huge departure from Wrightson's style, but one that would be atmospheric and give an equally dynamic visual style to the series.
A story that further convinced me Nino would be a great artist for the SWAMP THING series is one from
UNEXPECTED 152, Nov 1973. In "Dark Secret of the Swamp", a 7-page story written by Fleischer with art by Nino, an escaped convict finds his way to the home of a benign-looking elderly couple, but who have an odd habit of killing strangers, sinking their corpses in the bog, and turning them into mud-covered Swamp-Thingy-looking mud sculptures.
It was also cover-featured on this issue, illustrated by Nick Cardy, so you get to see Cardy's take on the same material. While not my first choice, Cardy would also produce an interesting take on SWAMP THING. And Cardy certainly demonstrated his talent for mystery material, on hundreds of covers throughout that era across DC's entire mystery line, TEEN TITANS and other series.
