We all know that the TOR network is always in need for more nodes, for the ever-increasing amount of users connecting but with average network capacity being nearly double what is required, which means TOR needs more location rather than just tons of bandwidth.
The problem at the moment with TOR, is that a government agency only needs to compromise a few server providers (OVH, Hetzner and Scaleway) in order to be able to track a large portion of the TOR network as TOR only avoids having multiple relay nodes in the same /16 IP block from being part of the same circuit, allowing an attacking to easily to perform timing analysis on more than 50% of the network if they compromise, just three hosts. This makes OVH, Hetzner and Scaleway, massive potential targets and as such all new nodes need to avoid them.
Of cause finding a hosting provider that no other relay operators have found would be ideal but doing that would be unrealistic as everyone knows how to search Google for “Unmetered VPS”.
If you ok with being on a network that contains other TOR relays, then you should look for hosts listed as being known as being good for hosting TOR nodes, like the ones listed here, but you should try to avoid hosting providers in the following countries:
United Kingdom (Heavy spying)
France (Too many Tor nodes)
Germany (Corrupt security forces and too many TOR nodes)
USA (Do I even need to explain this?)
Australia (Hosting provider could be forced to put a backdoor into your VPS)
New Zealand (Pro-censorship moral panics are common)
Potentially, eastern Europe might be a good place to run a relay from as there are a number of low-cost VPS costs there that also include plenty of bandwidth.