Anything issued to marines is good enough for everyone. While learning about hiking I bought a Katadyn Mini, it's a great filter, but slow. I would go with the MSR if I had to do it again.I like the MSR miniworks ex, 1 filter (replacements are $40) will last 500+ gallons, its lightweight (15 oz.) and totally field serviceable. With a few replacement o-rings, you can fix any problem with the filter (this is why its issued to marines).
Here is Backpacker Magazine's reviews of the best filters.I used to really like MSR products, but my friend had a MSR miniworks, which was made to poor standards, he brought it back on warranty 3 times and got the same problem with each replacement, then got his store credit back fed up.
I like kataydn, from the filters I have seen they are unrivaled in quality of construction and durability. although I am unfamilar with the first need filter posted here.
The last filter I used was a MSR Sweetwater Purifer system. It is a MSR SweetWater filter packaged with a 2 fl oz bottle of purifier solution (basically bleach). Total price is now around $90. The filter will remove bacteria and protozoa, but won't stop free floating viruses; the bleach solution will treat the filtered water to kill viruses.I searched but could not find a thread on this (although I am sure it was covered) so sorry but...
What's the best portable water filter under $150 for backpacking and short term survival use?