Honestly, I think that will have to do with your environment as much as the bookshelves. If the humidity in your area and your home is high, I would avoid closed bookshelves, and may even have problems with open ones. If your home is 30% humidity, I can't imagine you'll have a problem with closed bookshelves.

The glass doors look more finished for an office.

Average humidity is 50%. I'd say that closed is the best bet. It would at least slow down insects that feed on paper like silverfish, cockroaches, termites, book lice and mites.

BYW the Billy bookcases from Ikea are one of their all time best sellers for at least as long as 22 yrs when I started doing Ikea kitchens , I think glass doors look nice they have a finished look and for sure cut down on dusting.

I think it depends on how much you use the books. If you're constantly taking them out to use/read and putting them back, then you're probably going to find that the doors are open a lot anyway, so you might as well have open shelves. If they are not going to be used much, and are just for display, then glass doors are nice. If you have good climate control you shouldn't have a problem with humidity. And insects can get into cabinets with closed doors just as easily as open shelving.

Consider the door swing, how far in to the toom you have to stand to open it, and whether that will limit any furniture placement. My friend is a professor. Her home office is lined with glass front Billy bookcases on four walls. They have held up well over 20 years. I think glass doors make the room feel smaller.