The only prints I attempt without glue are PLA on smooth PEI. I’ve had over-adhesion issues with other bed/material/temperature combinations so often that it just is not worth taking a chance. I might change my mind if I were printing the same thing all the time, but most of my prints are one-offs.
Glue sticks are cheap but can leave marks on the print.
Liquid glues can leave a smooth surface, but are expensive.
I make my own liquid glue with cheap glue sticks and 91% IPA. The only problem I’ve had occurred when I failed to use enough glue in the mix.