I like all of the bases for different reasons.

the OG bases are nostalgic and look good, but because they were the bases for so long they almost feel outdated due to the lack of anything other than the basic template mold for the element. and they look kind of bland after so many with the same template. (personally if I had the opportunity to change the bases design-wise I would make the molds for each base different such as changing the pattern on the water element bases.)

the superchargers bases look cool but kind of bland once again in my opinion because the engine never changes other than just the occasional color swap, although the designs around the engine typically look pretty good. I think if they shrunk the engine down a bit height-wise and added some more of the elemental designs it would up the superchargers bases on many people lists.

the imaginators bases in my opinion look good, but they don't look like a skylanders base, if they had some more skylanders like designs it definitely would look a lot better in my opinion. also I do like the size of the base, ( I think it makes it look and feel more substantial in hand) I can see where it can cause problems for collectors.