I wanted to do some backpacking this past fall but never got around to it. I have an older MSR Mini Waterworks filter but was looking for something lighter and more convenient.
I watched a lot of YouTube videos and read many Internet reviews. I had pretty much come to the conclusion that there is no perfect water filter on the market. With that said, the Katadyn BeFree seems to be among the top choices for a lightweight, inexpensive system where viruses or chemicals aren't really a concern.
The Grayl appears to be a better choice in instances where the water quality isn't great and viruses might be a problem, such as in third-world countries. The Grayl does a better job getting rid of chemicals, too. The downside is that as the filter gets dirty, the water becomes more difficult and time consuming to press into the bottle. Also, the Grayl filters do not filter as much water as others before needing to be replaced.