Anime only, huh?
Dragon Ball ~ 21st Budokai Tenkaichi, mostly for Goku vs. Jackie Chun. Never watched the full anime, only seen scattered bits and pieces, the only arcs I really saw close to full were this and Search for the Dragon Balls, and I like this one more.
Dragon Ball Z ~ The whole Future Trunks part, but to be more specific, either Androids or Cell Games.
Dragon Ball GT ~ Hated almost all of what I watched, I guess Shadow Dragon mostly for the concept and benefit of doubt since I've seen the least from it.
Dragon Ball Super ~ Probably Universe 6 Tournament arc, it's the most consistent, and the only arc I feel the anime truly does better than the manga.