Cellulose is better on paper for r value but glass is better inside the walls as paper settles quite a bit. It's also much dustier to apply and in general.

I hope you like patching little spots in drywall. Every stud cavity needs a penetration. Also invest in a fiber optic camera boroscope, that way you can do am exploritory very small hole that's easy to patch before you punch a big hole saw in the wall.

Also consider going from the outside by pulling the siding, possibly replacing the siding and adding moisture barrier and properly sealing the windows and doors.

Another option to consider is the foam backed siding that's available. Along with new windows if you don't already have them.

Kinda depends on the budget.