what ist better charm with str or vita??

Str so you can do more damage, vita so you can get a bit more armor, i'd suggest str though so you can still do a bit of damage while tanking

all depends on the group you in, if you have 3x very good melee charcs that are all sitting in the back id suggest a vit charm to help you tank as much as possible. If your in a group without good damagers go strength instead of vit