I chose the Kyte 46 and my husband went with the Kestrel 48. It won't even be half full (basically only carrying 3 stuff sacks-about 12lbs in total) but I can use it for short wilderness backpacking trips here at home when I don't need/want to haul my 70L pack. I tried on the Deuter and Gregory ones but they had design issues I disliked and/or just didn't sit right on me. I have the advantage of having over 20 years of backpacking experience so I knew exactly what I needed and it took me less than hour to select the right pack.
I thought that the 36L would have worked just fine for me but I wanted a pack that I could use after Camino and that size is pretty useless for me. I hate over packed, busting at the seems, packs so I would never have bought the 32L. My other consideration (and my hubby's) is that if one of us is injured or sick and needs to lessen the load, then the other can take some stuff. We would never separated ourselves from our gear. Period. (if we are so hurt that a measly 13lb pack is too much to carry we probably don't need to continue) So having a little extra space also serves a second purpose. This is not our first long distance thru hike
This thinking won't work for less experienced pilgrims so I don't offer it as advice to anyone.