For me, it's the one that fits good. Stupid answer I know. But it's honest. I've tried various through the years and there's only been ONE that fit my back shape (when slightly hunched from riding) and where the shoulder and breast straps actually fit. It's some old cheap North Face something. I have some camelback things that are all completely terrible. I hate that company

Oh, and the pack I like has exactly ONE compartment and one zipper. Which means there's no wasted space on padding, pockets, compartments, etc. I can fit everything in there you just mentioned. I'm sure they don't sell it anymore as it's probably 10 years old now.