The most challenging maps for you.

Which of these heroes is the most promising: Mullich, Gundula, or Crag Hack? And where do you get him and level him up at the beginning – at the bottom or at the top?

This is a debatable question; it really comes down to personal preference. I would choose Mullich. And whether you start at the top or the bottom isn't crucial. You can always move him for 2500.