Here's what I am looking for in a relay at the moment:
1. Pulls in notes posted by those I am following from the relays they have listed as outbox relays in their 10002.
2. Allows folks my followers are following to also post to my relay if they want, but doesn't actively pull their notes from other relays.
3. Allows others outside of my WoT to post after paying a fee I set. Ideally allows me to choose whether the fee is per-post, per-month, or one-time.
4. Has administration tools within a GUI, including the ability to review kind 1984 reports to either act on them or ignore/delete them. This is NOT censorship. Just because I kick a note from my relay because I don't want to host it doesn't mean the author can't have it on 20 other relays where it's still available. Some types of content we MUST have the ability to remove.
Does such a relay implementation already exist out there somewhere?