For a serious middle relay — one that aims to sustain ~50 Mbps and earn a consensus weight worth its uplink — the Garrison ($11.90/mo, 4 vCPU, 8 GB, 240 GB NVMe) is the right starting point. The Tor daemon is single-threaded per ORPort but spends most of its budget on AES and Curve25519; the extra cores let you also run Nyx, a Prometheus node-exporter, and Unbound for resolver hygiene without crowding the relay.
If the goal is a guard relay (which the consensus promotes you to automatically after enough uptime and bandwidth), the Ravelin ($23.90/mo, 8 vCPU, 16 GB, 480 GB NVMe) gives you headroom for the higher circuit churn guards see — guards are the first hop for the entire Tor Browser population that picks them, which means more connections per second and a steeper RAM curve.
A Sentinel ($5.90/mo, 2 vCPU, 4 GB) can run a middle relay capped at 15–20 Mbps and it is a perfectly honourable contribution — the Tor consensus does not despise small relays. But the bandwidth/dollar ratio of the Garrison is so much better that most operators who start on a Sentinel migrate to a Garrison within a quarter.
What none of these are: an exit relay. Exits are a different conversation — different legal posture, different abuse-handling expectations, and a different platform conversation with us. Start with a middle. Let it age. Then if you still want to do more, we can talk.