How to decide which pool to join

[Raimy]

Try to find one with a server close to your physical location. You can usually find this out by the location of the server, in the case of multiple servers choose the one with the lowest ping times. For example, many pools offer a US1 and US2 server one on each cost, for me I have a lower latency to the east cost servers.

From there choose one base don its fees and general reliability. For Ethereum I have found ethermine.org and nanopool.org fairly reliable, low fees, and both have servers close to me. You will want to have a short list of two or three different pools anyway so you can configure backup servers in case your main pool goes down.