I'm 6 foot and I feel like 4xl is good casual. Get an XL. The sizing is really weird on them. I think my 4 XL is 32 inches long which is a normal 2xl or XL Jiberish so they run very small.
i'm 5'10" and i've owned 2xl and 3xl puffehs, they fit almost exactly the same, and are perfect for just regular wear. you have to be kinda short and get a 5xl to wear it for skiing. if this changes your mind, i have a 3xl maple puffeh..