Keet = no setup networking, direct P2P

Simplex = use relays, or setup your own server

Simplex has better metadata privacy design just because that is something it specifically targeted. While something like Keet is just trying to remove central servers and third parties all together. Keet avoids bandwidth bottlenecks for files too since it’s direct P2P. Not sure about Sinplex there and relays.

The reason I would lean toward Keet is simply that you won’t really need to explain to people how to use it. You just share links and join rooms. Encrypted, P2P, no servers, and all that good stuff by default and without any networking confusion.

Simplex would probably be better if you are trying to get more robust network layer privacy, but I would only share it with people who are technically inclined generally.

(Also only have a vague understanding of Simplex design, so if anyone can point out a mistake I invite you to join)