Ultima IV and Ultima VII: The Black Gate are widely regarded as the high points of the series. The Runes of Virtue games are mostly forgotten afterthoughts, but

Ultima IV and Ultima VII: The Black Gate are widely regarded as the high points of the series. The Runes of Virtue games are mostly forgotten afterthoughts, but they're supposed to be decent games for what they are (action-adventure games). They're not representative of the mainline series, however.