If you plan to have one service only, then it seems you don't need an ESB. Also, the properties of the service you mentioned (resilience, etc.) should not affect your decision as an ESB will not help you solve this type of issues.
If you were to have several services that perhaps even interact between each other, then you might need to provide transformation of protocol/transport between them, perhaps orchestration, monitoring (SLA) and statistics, common security, etc. In that case you could think about having an ESB that would handle this for you.
Again, think about how your whole "business" will look like in the future.