As Robert told you above, really the need of resources goes from the usage pattern you community will have.
Faster cores will help Discourse to do things quicker which could make it feel snappier but more cores would allow yo to do more things which would allow you to spread more workload and even maybe (a big maybe) serve more people at the same time.
If you really need that kind of configurations (more than a core and 2GB RAM) I recommend you to do some testing first to see which resource you’re the more scarce and with that you take a better decision.