Once you have the rest of your kit sorted, only then can you decide your maximum load and settle on pack capacity.

If you're there, then there's a dividing line between frame and frameless separate from volume. Over some unknowable weight (based on the individual, not some all-knowing table) a frame is very helpful. Frameless packs can work with a surprising amount of weight if they fit perfectly.

Finally, a big pack, especially a frameless, needs load control to reduce volume as food is consumed in order to maintain structural integrity. Ironically, a lighter load in a saggy pack can be less comfortable than the same pack stuffed to the gills.

I'll suggest trying every pack you can get your hands on, loaded, and evaluate fit and flexibility and fit.

Happy shopping,