My LGS is doing a night where everyone plays using a legendary artifact as their commander. What are the strongest options?

Title. There's a couple of nights we're doing soon where everyone is making decks except using a legendary artifact as the commander instead of a legendary creature. All the same rules apply, so colour identity matters etc. And if it changes zones it can back to the command zone. What are some of the strongest options? And what sort of decks could be built around them when you always have access?

I don't think there are any banned cards except we've all agreed that the one ring isn't allowed. Thanks in advance.