I've been thinking about this for a little while now and I think Fedditor is the best choice.
- Between Kbin and Lemmy, there's already two choices of software platforms for Reddit-esque link aggregators that work together. In the future there may be more. I think the term should be inclusive.
- Fedditor is play on redditor, a widely used term for users of the privately owned Reddit. A fedditor is a user of a Fediverse alternative.
- Since ActivityPub is an underlying protocol that interfaces with the rest of the Fediverse, I think emphasizing the Fediverse aspect and the "reddit-esque" aspect is more important than the specific software platform.
- People may use different terms for Kbin vs Lemmy vs future alternatives (or ones I just don't know about), but they may also use different terms for the instance they use or for the magazine/group that they are a part of. I think if any term becomes widespread, it should be an inclusive term that fall underneath a more general term such as Fedditor.