best nations in each era

[Snacktime]

Hi - I know I've seen threads on this before, but I can't find them. Can someone either link those past threads or discuss here what are generally regarded as the best and worst nations in each era? I am trying to start a game with a few noobish friends and we want to choose nations of rough equality. I played a lot a few years ago but my god it's hard to remember this stuff. Thanks!