Hmm... I have the opposite experience – for example, just the cost of building a single Sanctuary is quite high. The Monastery also requires a lot of resources, and Angels, both building and hiring them, seem to cost more than Dragons. As for the Elves, all you need to do is find enough wood, and by week 2, you'll have a decent army. Plus, if you have 10 stone and 20 crystals, along with enough gold, you can get Dragons and Unicorns, and they're quite affordable.
This is what I meant by development speed.