I'd keep doing what Tom is doing lately on his eras. 7k for #1 and some for the rest. That way even small alliances or new players get the tokens. And then they can keep fighting for more.
Atm Tom does like: 7k for 1st. 600 for 2nd~5th and 500 for 6th~10th and I already see ppl fighting to get at least rank 2nd~5th instead of 6th~10th (80% of those fighting were new players).
It's something that need to be constantly on change and need to make test each era, make it dynamic, change rewards give some motivation to fight. Every era the same shit.. it gets so boring. For the 1st time I'm liking Tom.
For medals, have nothing to say I always try my best to give all top 10 to my team.
About AI colonies, oh well.. It's a game, turn based game, if u play it u must be active, it ain't no more sit, boost and build if u do that, actives players will get AI colonies and get stronger than u (in a long term, till set a good income to match Boosters).