I've only finished Dragon Ball and liked that one a lot. Seven deadly sins is my favorite anime and I've read most of the first season of its manga as well, and it was pretty good. Haven't tried One piece or berserk so can't say about those.
I read/watched a good amount of manga/anime and always saw the country farmer boy with a straw hat and long arms and thought what idiotic manga that should be .... until i started, from curiosity, reading the manga and it is the only one i still read today. You are not going to regret it. I recommend reading it first and after that watching the anime.
So Berserk is one of the people's favourite (also mine) it seems. but i would like to recommend also:
Gamaran, Feng Shen Ji, Kingdom, Boku no Hero Academy, Tokyo Ghoul, Ubel Blatt and also, for those who love Berserk, Priest manhwa (it isnt finished sadly)& Shin Angyo Onshi. Have a good time reading ;)