I have the Genisis Project mod. that means any planet can effectively have ALL THE TILES.
the AI uses the (poor, IMO) Governers system and seems to pick basically randomly.
in this case, a 'balanced' world will end with one 'superhex' of factories (that is, a Power Plant surrounded by Factories), one of Research (co-ordination center+labs), and a variably-sized number of economic, entertainment, and food buildings*. an Industrial world might have a couple labs or whatever to take advantage of tile bonuses, while a Research or Wealth planet will sport a PP and a factory or three but mainly their respective focus.
for the record, in my typical games three-four balanced worlds feeding a shipyard are perfectly capable of pumping out contemporary Large warships in under ten turns- throw an Industrial in the mix and you can throw out a Frigate every turn. my suggestion is to vary your approach based on both the era of your colony's founding and the bonuses you get on-planet- putting Manufacturing on a Ghost World is a wast of its 50% Research bonus, and a world with two Manufacturing tradegoods and a couple tile bonuses is a shoe-in for Manufacturing. and so on.
frankly, I tend to end up playing a Balanced homeworld most of the time purely out of necessity- Research so I don't get out-teched by the AI (too much, Fucking Alterains,) Production so I can do landgrabs, and wealth just to keep my empire from imploding with debt. honestly, though, with the latest update I've found it more efficent(not to mention more lore-friendly!) to just grow more people if I want more production, since more Pop equals more everything, including tax revinue to keep your nice big fleet in bullets and burgers, as it were.
*I generally aim for what I semi-jokingly call a 'konoha', that is, Food distribution surrounded by farms with a Hospital stuck somewhere along it so it gives two farms adjacency- which can be expanded into a 'pill' around the Hospital if I really need it (hint: I rarely need it) and well, 70+ in all attributes without a focus checkmark speaks for itself. and that's when there isn't any Manufacturing or Population bonuses, the actual average tends to push three digits...
