Like I said, they were all good episodes. Crawling Niceness is the best, but the other two are pretty good.
Crawling Niceness: I love Jeff the Spider! When I first saw him gigantic, it made me LOL. But when Billy calls Mandy at 3AM because there is a "very scary bug" in his room, it was just hilarius. Also, another highlight is that cowboy in "#Killmobil 17", especially "I'll need a big boot" line.
Smarten Up: Another great episode. It was a bit plotless, but Milkshakes trying to teach Billy had some very good laughs.
Grim Show: Yet another great episode. There were some very good lines, and the funniest scene was Grim's show, the scene with the Dracula. Only the ending scene was bad, but I guess they couldn't think of some other way to end the epsisode.