For beginners, the Contabo VPS is suitable. This is a very good and stable VPS that works great with a bot. The "VPS S SSD" package is more than enough to get Gunbot up and running. Final monthly price including Windows Server 2016 is 9 € / month (with Linux OS 5 € / month).
A more reliable VPS with better network connectivity would be www.scaleway.com with DEV1-S package for 3 € / month, but this VPS only has Linux OS.