Saw the Viking ship being sold MISB at a recent convention in Toronto. If I had had more money leftover (it was my third con of the summer), I may have gone for it. It's a very nice looking set with some beautiful box art.
I've always really wanted that fortress set.
I'd say that the Elves dragons and some of the Ninjago dragons are up there too. But I totally understand why you like the viking ones. They have a slightly abstracted "edgy" aesthetic that has a lot in common with the Dino Attack dinos.
Anyway, I'd love to track down some of these sets to review on my YouTube channel. That double catapult set has a really interesting-looking dragon (it appears to be made using mostly Knights Kingdom II action figure parts).
Also, the prints, of my gosh the prints! Sooooo many beautiful shield, torso and even tile prints in these sets.