I really hated what Joss did with Spike in the later seasons.

Wesley, OTOH, only became himself in Angel. In Buffy, he was just the jerk of the season, mere comic relief. I loved how Angel made him a full-fledged character, with a background and a convincing motivation, including character growth and stuff.

Unfortunately, I abandoned Angel after 2/3 of Season 2 and only watched the later seasons sporadically. Didn't very much like the direction the series took afterwards, but perhaps the_wild_iris can persuade you that it wasn't so bad, after all. She likes the later seasons.