Conc is much safer with better synergies; you can get high damage, defense, life, resists, blocking, and pdr with the build, without any real fear of death. You can leech mana and life back with each attack and you don't have to be concerned with faster hit recovery.
Berserk can do EXTREMELY high magical damage, which is great since most enemies don't really have a lot of magic resistance. Problem being of course that the synergies are kind've strange, you have no defense, and you have to have great faster hit recover/faster block. They can be very powerful, you just have to be a lot more careful an really learn to use skills like howl, taunt, and warcry. They cannot leech back their life/mana with their main skill.
I would go with conc myself, but of course, I wrote the book, hah hah.
-Hal