The three precursors that give +5 alloy, +5 gas are actually really strong. Assuming you push hard for them with lots of science vessels surveying in the early game, you can get a fairly significant bonus that leads to snowballing. Because early game expansion and development is most critical for snowballing in both military and tech, in the long run I'm fairly certain that these precursors are actually much better than people think. For example Cybrex Alpha starts you out with a Ruined Ringworld -- this will allow you to get Mega-Engineering early but other than that you can't actually use the Ringworld until you spend tens of thousands of alloy, making it useless in the early and mid game. Fen Habbanis is probably still the strongest choice, but if you cannot use population controls then an ecumenopolis in the early game is dead weight because you can't grow the pops fast enough to really take advantage of the huge districts.