I think the movementlabs testnet campaign is the most engaging one ever designed. Usually testnets are quite dull, and geared towards devs, and not really optimised for building a community. But Movement is different. Beyond just my own opinion, I've seen many users comment that this testnet experience is genuinely fun. 
It's very gamified, with users being able to choose one of six guilds, with quests specifically curated for each guild. You earn higher level relics as you complete more quests. The testnet activity has been enormous (yes, I'm sure lots of bots alongside real testers). They have 54 apps live on testnet, showing real interest from Move and EVM devs.