If you find authentic Ultima 4 too painful/primitive/boring/whatever, then an alternative is the NES version. It's been Nintendo-ized making it play differently, but it still follows the original enough to serve as a standin for the PC versions if those aren't enjoyable to you.
The Sega version is much more authentic to the computer versions, it appears they only changed it just enough to make it playable with a controller instead of a keyboard.

And the Sega graphics look much more advanced IMO