Achievements? I love achievements!! Lots of achievement... But I can understand that some people don't so an option to "Hide" or "Don't Track" achievements could be good.
I like the idea of tracking statistics (total iron mined, biters killed, power poles build, etc) and I would like to see these be done as both per-game totals and account totals. This would open up a lot of options for achievements (X something in one game, 1 billion iron mined). Additionally I can see where stats could be used by mods or server plugins as different ways of scoring competitions. If stats were to be tracked by your account I would like to see an option for not adding game stats to your total.
Of course, tracking stats and cooperative multiplayer can create a complication of who gets credit for what. I consider that a secondary detail that can be worked out instead of using it as a reason whether or not to do it.
Regarding multiplayer and gaming styles, I am absolutely a coop player. I do not care of PvP games, just not my thing. But, Factorio PvP multiplayer should be a thing.
Regular reports on Factorio development.