Sawyer mini for me. But it's a filter, not a purifier. I just don't have a need for a purifier in the areas that I frequent.
Pros:
Lightweight
Compact
Versatile
Low Price
Cons:
Slow when using as a gravity filter. Moderate if you can apply pressure.
When used as an inline filter to your water bladder, there is some resistance. Similar to drinking a milkshake through a straw.