I use AniList, Anime-Planet, LiveChart, AniDB, and MyAnimeList

Reasons I use each:

AniList gives good stats and breakdowns of what genres, etc, you tend to prefer in a clean, user friendly format

Anime-Planet gives me generally good recommendations, based on anime I want to see something like, or my overall library preferences

LiveChart's just good at giving me what I'm looking forward to in a good digestible feed. Sometimes I scroll through past seasons to see what I may have missed, this is why I maintain a list there

AniDB gives incredibly detailed analytics, has a cool timeline of all your anime watching history. I think this is just really satisfying to look at

MyAnimeList honestly doesn't really have much I care about, just people tend to get squirmish if I link them anything else, so it's the easiest list to send to people without having to explain why I don't use MAL