MartianManIm 5'11, and I wear a Jiberish hoodie in size L, and it is pretty roomy on me but probably not baggy. My guess is a XXL would very baggy on you. A 5xl would be ridiculous. IMO, anything over XL on a 5'8 guy just looks dumb as fuck, but that opinion isn't shared widely on NS. If you want baggy, than i think a XXL will more than enough. But to each his own.
really? I'm 5'11 too and the arms on Jiberish Larges are too short for me... maybe my arms are just long? dunno. But yea I'd go with a 2xl probably for you, 5xl's go down to my knees and not really in a good way either haha