I suspect that there is very, very little difference between the SNES, PCE and Genesis in terms of their practical, technological limits on doing sprite animation. They all have the very similar bottlenecks in terms of color, pixel bandwidth, and memory. It's a fairly unremarkable thing to compare, IMO.
The reason why there's nothing like the best Genesis stuff is mostly because nobody made it. Even Treasure said in an interview that there's not really anything that special about moving a few sprites around together. The important thing is the artistic vision to make it look good.
And the rest of the game looks like meatgrinder sauce? I think that drac x shows some of the nicest back ground presentation in the whole 16-bit game era. so many details, so much variations, so much graphical content overall. no other akumajou game came just close to that. not before the 32-bit era was ringed in.
The backgrounds are kind of hit and miss, though. Some of them are technically and artistically very well done, like the final third of stage 1 on the normal path. For every moment like that, though, there's another like this:
or this:
I actually think CV4's environments are much more interesting to look at overall, in spite of a couple of odd palette choices. They may not win the background-tile count, but they move more interestingly thanks to all the layers and effects. If you were to describe the scenes with words rather than tile-counts, they also hold up very well in terms of amount of detail.
Once you get past the flashy cutscenes and high-production music in DraculaX, I think the game's greatest asset is its bosses. Not only is their size, color, and animation the best in old-school Castlevania, but their
behaviors and the tactics they demand to beat them are the most sophisticated as well. CV4 does really badly there, and CV3 and the X68K game aren't quite there, either. That's what I'd tell a first-time player to focus on and try to appreciate. The backgrounds, not so much.