Anonymous
In the 1990’s I was doing a lot of backpacking, living out of my pack in the woods, hopped some freight trains, wilderness living, living in a teepee, etc. During that time I was also working at outdoor retail stores (to get the discounts on the gear for my adventures.) I used a few different filters made at the time and here are some of my experiences.
The PUR brand at the time, since purchased by Katadyn, had a filter called The Hiker. It was a simple filter with a screw in fiber and activated charcoal cartrige that worked well with clear water, had a great flow rate, was inexpensive, but was not cleanable. I used this filter for a while but the lack of cleanability was an issue. The pump on the unit was easy to use, with a good flow rate. But once it clogged it was not field servicable without replacing the entire filter cartridge. (the Hiker Pro is still made)
I then used an MSR MiniWorks filter. The ceramic filter was cleanable which was what I was looking for, but the flow rate was slower, the pump took more strength to use and was made up of a lot of little moving parts, plastic, o rings, etc. I found that the ceramic filter clogged quickly and had to be cleaned often. Also, when a ceramic filter is wet if it freezes it can crack, making it useless. Not a common problem but one to watch out for. Also, throwing a backpack off a moving train before getting off the moving train causes a lot of shock to the gear in the pack. Not the best place for a ceramic filter. (MSR Miniworks stil on the market)
I also used a Katadyn Pocket filter. Made to last with aluminum construction, it was the highest quality filter I used but heavier and slow flow rate. Flip side is one filter can clean about 11,000 liters of water. Well worth the long term investment.
I used a Katadyn Combi filter, it was a piece of $%^ not worth the money or the weight to carry and was ultimately taken off the market cause it was junk.
So I tried a Sweetwater Guardian filter. It was light, inexpensive, few moving parts, cleanable, it could freeze without damage, had a good flow rate, drop it without cracking it, etc. I used it extensively in 2011 when I did a bicycle tour from Washington State through Oregon, to Northern California. It was a great filter. Only problem, MSR bought out Sweetwater and stopped producing this filter around 2017. So it’s off the market, MSR killed the product off. I lost mine when I needed to exfiltrate myself from a sketchy situation and had to leave my gear behind.
Since 2011 I have primarily been car camping and bring my water from a municipal water source so do not have much experience with the newer filter technologies on the market.
Looking at everything out there, and the experience I had, the filter I would buy now is the Katadyn Pocket Filter. It has been on the market longer than any other filter. It is made of high quality machined aluminum parts, it is tried and tested and will last. But it is expensive and relatively heavy.
I now keep an unused LifeStraw and Aquamira water purification tablets in my BOB just in case. I find that the more moving parts something has the more likely it is to break.