At times Shadowrun had some really good graphics, though of course I love it for the gameplay. I agree Landstalker had pretty well-designed and colorful graphics. Even if the sound was designed to drive me mad, with all its bwoops and swishes and AAAGGGGHHCK! cries when the enemies died... Let's see, Streets of Rage 3, which had some pretty impressive arcade-like graphics (so did 2). Oh! The Lost Vikings had great very colorful graphics, and of course so did the Sonic series.
Now, I'm pretty surprised that nobody mentioned Phantasy Star IV.
So to sum up, everything mentioned by others plus Shadowrun, Streets of Rage 3, The Lost Vikings 1+2, Phantasy Star IV.