The Man-Thing book is the first volume of a series collecting Steve Gerber’s work on the swamp monster. Gerber was wildly original, and even early in the book you can watch him crank up the crazy. During this period, Marvel published out a lot of books with the only the lightest editorial interference, leading to an anything-can-happen vibe. This is most apparent in Gerber’s work.
The other book is the massive Werewolf by Night Omnibus, an oversized thick tome (over 1100 pages) collecting the horror/superhero series. A variety of writers worked on this, Doug Moench being one of the best and the one who stuck around the longest. The early issues have terrific Mike Ploog art (he’s also in the Man-Thing collection, and worked on early Ghost Rider and The Monster of Frankenstein for Marvel). I also have a real fondness for the art of Don Perlin. He stuck around Marvel for a long time and did solid work on Ghost Rider.
So excuse me while I plug in the lava lamp and travel back to the early 70s, when gas was cheap and so were the comics.