I don't think it's the "most sophisticated," but it's DIY, and it works.
https://minibolt.minibolt.info/bonus-guides/nostr/nostr-relay
It's the client's responsibility, based on the user's preferences, to adapt and filter the information they receive from the relays, in addition to giving the user the option to select which relays they want to connect to. As you mentioned in your first podcast with nostr:nprofile1qy2hwumn8ghj7etyv4hzumn0wd68ytnvv9hxgqg4waehxw309anhyet9deek7atv9eehqctrv5qzqqqqqqqgyll6499lag5gc00uu3pzc720hwtxykmtx85sf8mjn4cqz56m90 about nostr, the relays are and **should be** "dummies" to preserve the nostr anti-censorship essence.
Anyway, if that's what you're really looking for (idk):
WOT relay: https://github.com/bitvora/wot-relay
Bostr (proxy): https://github.com/Yonle/bostr
