Based on my experience, there are currently only two options for a "guaranteed" quick and good start in the game: through machines or through a strong mage, like Minasli.

I didn't find machines to be very effective. Even for Elves, with their additional skills... You level them up, level them up, but the output isn't that great. A mage hero can achieve similar results more easily, and a fully upgraded machine skill tree can hardly even come close to the effectiveness of a fully upgraded magic skill tree.
Unless building mage guilds is more expensive than buying machines.

Well, there's also a third option: using storm arrows for Orcs.

What's good about Orcs is that their hero's attack power is comparable to the power of direct damage magic, at least in the early game. So, for a good start, they just need to take the corresponding perk.