Round table

You start with Barbarians, and yet Crag is significantly stronger than Gurnisson!

I always choose Gurnisson as my starting hero for the Citadel. Let's estimate how much stronger Crag at level 10 is compared to Gurnisson.
Crag's damage increase with experience: 1+0.3*(1+0.05*10)=1.45 times
Gurnisson's damage increase with experience: 1+0.3=1.3 times
1.45/1.3 = 1.115.
Conclusion: Crag's damage (at level 10) is 11.5% higher than Gurnisson's.
However, the ballista is very helpful for defeating neutral creatures.