Discussion of level 1 monsters.

If you pit one unit of the first level against another, the Berserker will definitely win (unless the Fairy gets lucky with a critical hit).

Here, one could argue: a Centaur would significantly reduce the Berserker's health before he even reaches it. And in general, if you're going to conduct such a "competition," you should compare not one-on-one, but based on the weekly production rate. That's where you'll find out who wins. In that scenario, the Fairies have a good chance of winning!