Since people are talking hydration packs, rather than small packs: I went Camelbak -> Deuter Race EXP Air -> Osprey Raptor 10? -> Camelbak LR.
Camelbak stuff is light and has well thought out details and has an excellent ownership experience. I like the Camelbak bite valve and roomy zipped hip pouches. Straps are kept in check with elastic bands, no need to trim. The lowrider bladder is a convincing design, and I like the hose quick disconnect, but find the filling cap closure fiddly.
The Osprey is heavy duty. The fabric is so tough that it causes abrasion damage on my other clothes. Plus Osprey straps are super long and need to be addressed, else they're streamers.
Deuter's suspension system is excellent. The source bladder's opening is excellent. Just lacking in a quality ownership experience/satisfaction, with a few personal niggles, like aesthetics (inc. shape, size).
Simply put, Camelbak's LR designs are top tier. They're the ones I compare all else to now. Wingnut bags still catch my attn though.
Never really used a small pack. I've tried fanny/hip packs, but they loosen and droop.