Usually just one bag, and which one really depends on the type of travel, and whether or not photography is a priority. Also, since I shoot two vastly different arenas (nature and paid events), the bag choice can vary. But for the sake of this thread, we'll just say I am shooting for leisure, on travel.
Minimalist: ThinkTank Turnstyle 20. Fits 5D4 + 50L + 16-35 + 100L.
More utility: Thule Aspect. A few weeks ago I was walking around in NYC, it was rather chilly, and I got sick of juggling hat, gloves, camera bag, coat, water bottle, snacks, etc. So, I went to B&H and searched bags that offered camera storage + personal item storage. There's only a few bags that ticked those boxes that weren't gigantic and bulky. In the end, the Thule Aspect won out. It's affordable, inconspicuous, and it holds a good amount of stuff. It actually fits my 400 DO II w/ reversed hood + 5D4 + 100L, and other personal items.
Full Kit Base Station: ThinkTank Street Walker Pro. When it's time to travel and take EVERYTHING, plus a laptop. It'll usually stay in the hotel/relatives house, and the Turnstyle 20 serves as the day-pack.


