I've used a bunch of different filters etc. over the years for back country fishing and hiking. It depends on how much you are willing to carry. I've found the Katadyne Hiker Pro to be probably the lightest and easiest to use. Many times there will be several of us camping/ fishing for several days. the filter will fill a Camel Bak in short order and so far no one has gotten even the slightest bit sick.
Last year i picked up a Steri Pen. Costco had a combo pack. Water bottle, filter cap, regular cap and steri pen. The only issue I had was that it was slow to fill. Plus it takes a few min. for the pen to work. One of the sales people at REI said that they spent several weeks in countries where the water was suspect even in restaurants. they would just keep the pen in their pocket and stick it in the glass and stir.
For a short day trip i would usually fill the Camel Bak and maybe have an extra couple of bottles in the truck. Now if the Steri pen would work in the Camel bak we would be set.