I'm just old fashioned enough I *like* holding a physical copy in my hands. When they actually do art and add flavor to guides, they are worth the monies.
Alt-tabbing to read a PDF though....that doesn't even fly with some of the more recent games.
The only games I ever feel I need guides for are RPGs, usually JRPGs. American RPGs are too cut and dry, and tend to lack the secrets and features that JPRGs made so popular. (Games like Planescape: Torment are the exception.) For Atlus games like Shin Megami Tensei....yeah, I like having guides for those games.
Or the games where the devs made puzzles and secrets so ridiculously obscure, you NEED a guide to even know they were there. Damn near no one does that anymore, other than open world games with their damn collection achievements.