After a couple of years into GTD, I've switched to the Bullet Journal method just over two years ago. One of the things I really like is the monthly migration. It gives me the opportunity to reflect on tasks before migrating (copy/paste by rewriting them by hand) to the next month. Some of those tasks don't make the cut (= saves me time and less mental 'weight'). Especially when some of those asks have been migrated from one month to the next a couple of months in a row.
Sometimes I try GTD again in my work. But after a few weeks I always go back to Bullet Journal.
Over one year I switch for two years to the bullet journal. It was working quiet well with me except that I realize it tooks me a lot of time and it efficiency was not like GTD. I also enjoyed the monthly migration until I realized That I could do the same in Omnifocus. But things gets harder and a bujo last me 2 month and I had to make a general index for finding my stuff from one to the other (even if I followed the monthly and yearly migration). I felts uncomfortable. I was missing GTD even if I was conscious needing to learn a lot about it.
So I decided to go back at 100% to GTD. I made a habit I call it "my monthly clean up" where I look at all Omnifocus list and erase all which needs to be. I just doit with the 2 Ryder's question of the monthly migration and also just taking space to evaluate my engagement regarding to my H3 >H5 horizons. I often realize that some projects are irrelevant and some others need a NPM.
I also make reporting of what I do day by day on a weekly paper sheet adding just one task after it is realized with the rapid logging. it makes me understanding what happened and why. I also let me understand how I could improve myself. It is by this way that I realized I needed a real brush up with GTD ! or that I was working with a client who tooks me too much time for my return on investment.
Then after evaluating this paper sheet each week I archive this paper sheet in my reference binder. I can see at a glance a kind of historical reporting.
About my opinion, the twos methods are not so far away one from the others. David Allen even dedicated it. They have a lot of common points. Bujo could work for me if I had some little engagements but when things are getting crazy like they are now
I only fully trust GTD. With a little time it does the best. And If you add a good software well configured it is just incredible !
So, anyway the bujo is interesting but, for me, not as complete as GTD Is If you get the control part and the horizon part even partially the results are just amazing and you have more results because it is structured and you can get a real help from the GTD community.
Now I am fully GTD and use my bujo for Journaling. This kind of journal is different than my Daily weekly reporting. It is an emotional journaling where I let place to my feelings about my life. How I feel, why, what happened about a client or a friend and how I felt and why. It is often short but it helps. Sometime it makes new projects, new H3, gives me a new vision H4 and sometime has a deep influence on my H5. Last year I read all my journals at a batch, taking notes. It took me about 3 or 4 hours but it had consequences on my decisions...
The 2 journaling processes are in my OF references for not forgetting and do them on regular basis. It is just a list I see once a day which contains my habits.
Hope that helps.