I find that internal frames fit my medium back a lot…
Design: Top-Loading Interal
Size: 5400 cubes
Number of Pockets: 2 in top, large mesh pocket in front, 2 bottle holders on the sides
Max. Load Carried: 62lbs
Height of Owner: 6ft
Price Paid: $209.98
I find that internal frames fit my medium back a lot better than external. I found Osprey Aether 90 was perfect choice when I go winter backpacking. I needed the space and this answered it. Super comfy, moves with my back in harmony. And you can't beat a lifetime warranty.