Common Mistakes:

• Gigahertz Myth: When selecting CPUs for your Minecraft server, do not use the clock speed rating to compare two CPUs unless they are of same model and manufacture. Please refer to Gigahertz Myth for more info. In short, select the latest cpu architecture and the highest single core thread rating model available.
• More RAM ≠ Better performance: Server performance is largely dependant on your CPU, not RAM.

Personal preference:

• CPU model: I personally wouldnt settle for for anything older than AMD Ryzen 3900. A generational leap is significant. Generally, looking for a newer CPU that is marketed toward gaming will be the most suitable for Minecraft, as these tend to have higher single-core performance.
• High yield, high risk: Some hosts with huge specs manage to fit in here, despite the anti-summerhosts rules. They're often dangerous because they're unstable and remove themselves or restart their service to wipe the customers clean in just a few months, all so they can renew themselves under new names. I strongly recommend choosing a smaller host with reasonable specs.