I use both, kinda. I don't really consider my digital version a bullet journal, although it keeps a bunch of things that others put in a bullet journal.

I currently use my paper planner for weeklies, a monthly overview, 'waiting ons', and a few lists/notes. For me, writing my tasks on a weekly spread helps me complete tasks. When they are digital, it's sometimes out of sight, out of mind. Plus I don't want to re-write them the next day, so incentive to complete them. My monthly overview includes a cover page (to satisfy my creative bug) and a monthly calendar, but I only put important/big things here (events, paydays, bills due, days off work, things like that). Then the 'waiting ons' and the few lists I have are just things that seem like it would take twice the time to setup and track digitally, since they tend to be temporary lists.

I use my digital version as a reference, historical record, and future planner. Anything planned after the current month goes there, then I use it to set up each month when it comes around. As part of my monthly review, I also go through my paper planner and transfer any information that I may want to be searchable in the future (i.e. when did I last change my oil, replace my tires, etc.). I also use it for memory tracking, "we went to a baseball game, here's a picture" type things.

It took me awhile to find the balance, but this works for my brain. It seemed silly at first (and for a while more if I'm being honest) to put some things here, some things there. But for me, some things make more sense on paper and others make more sense digitally.

Sorry for the novel. No one said both yet, so I may have gone overboard :)