Most of the games I'd mention have been mentioned already -- Street Fighter II', Legend of Xanadu II, Nexzr, AnEarth Fantasy Stories, Spriggan...
Beyond that, hmm. For regular CD titles, what about Alzadick or Download 2? They look pretty good for games that don't use the Super CD. Also I personally really like W-Ring, both in visuals (for a HuCard) and particularly the music. And on that note, how about Gradius II (Super CD)? I see Super Darius 2 mentioned here, but Gradius 2 looks just about as good I think... as for Gradius 1, it obviously can't match the sequel, but for a HuCard game it looks great, slowdown aside.
Otherwise, hmm. Well, the best-looking RPGs are probably Xanadu II and AnEarth, but Magicoal and Monster Maker look a LOT better than most any earlier Turbo RPG. Great work there compared to the earlier stuff.