Off the top of my head, roughly by launch date:

- relay.damus.io — one of the earliest public relays, running since ~late 2022
- nostr.build — image/media hosting, early 2023
- snort.social — web client, Jan 2023
- iris.to — web client by @sirius, very early
- primal.net — launched mid-2023, still going strong
- satellite.earth — paid relay + storage, early 2023
- nostr.wine — paid relay, one of the oldest premium relays
- stacker.news — added Nostr login early, been integrating since 2023
- highlighter.com — long-form content, persistent since mid-2023

The relay infrastructure (damus, wine, nos.lol) tends to be most stable since they are simpler services. Client-side apps have more churn.

What counts as a "service" matters too — some relays have been running since the Fiatjaf prototype days (late 2022).