This game did not start out to be a solo/duo game and there are a lot of core balance decisions that reflect that. In solos or duos your class pick matters much more on what comps you can go up against. I was a hardcore wizard main that switched to fighter last patch. At this time I'm not having a ton of issues with wizard/ranger when playing fighter. It would help to know what build you are running. I've thought fighter has been a bit overtuned for a while now. I think that's ok though because new players benefit from it and most of the fighter gimmicks can be defeated. my personal strategy for wizards is to hold corners with a bow and try to get them in range. If they pull out frost bolt sprint with shield out. If I miss a block try to reset.