Bottles. Wearing anything heavier than a shirt on my back and neck sounds horrible. Let the bike carry the heavy load -- that's why I got it.

But I'm biased by physical limits. My C2 vertebrae is splintered from a car wreck, so I can't carry heavy weights on my neck or shoulders. That's why I prefer cycling over hiking or long distance walking. If I can't carry it in a waist pack, it doesn't go.