OpenRA

I normally go:

power plant
barracks (start building infantry)
ore refinery
2nd ore refinery
armory
radar station
heliport

first things I build in armory = 1 ore truck, 2 light tanks, another ore truck, when radar is finshed 2-3 artillery, when heliport is finished hind

any others ? maybe also depending on map size ?

there is no "best" build order ...

it depends on map , spot position , team or 1v1/ffa , how good do you know your enemy

and every build order has its weak points ... it also depends on , if you´re more the risky or cautious player ... agressive , reserved or sneaky

good players use various build orders ... they play every game different then before , otherwise it would be just a matter of time to loose ...

I agree that there's no "best" build (at least, not determined yet) but based on the matches I've been watching an early resource advantage is pretty decisive. So more ore trucks is almost always a good idea, unless it's a small map and/or your opponent is applying pressure. If your opponent isn't harassing then expanding early tends to pay off pretty well too, although that is definitely more situational and you have to be careful you don't spread yourself too thin.