**Edit:
-Anything with holes larger than .03 micron is not worth owning. .03 will work on the big nasties (cysts etc). .02 is preferred but not a necessity.
-The monolithic filters should be under 50 bucks no matter what.
-Pumps are great however in a fast paced setting grab and go is preferred you'll want a suck through for your BOB and a pump/drip for the house
-I forgot a third chemical option. MSR Makes a pen tube that produces its own natural chlorine from salt and electricity it belongs with katadyne pocket (would make the ultimate pair + maybe a couple 50 packs of tabs)
What are your intended uses?
As far as a filter that everyone should have I think every household in America should have one Katadyne pocket + a mono drip bucket setup end of story.
However...
there's more to it.
Do you want to just filter normal stream water that is from a fresh source (low virus chance)?
What happens if you want to drink dirtier water? what if there is livestock in the area or dead bodies etc?
You will also need some form of chemical treatment for viral threats. At home boiling would be the ideal however out and about boiling can be hard to come by so chemicals are your best bet.
There are generally two paths followed on chem treatments either chlorine based or iodine based. I myself prefer the chlorine tabs. You still need to drink the water through a filter but at least the viruses will be dead (gotta filter the bodies jk). The packable filters that have some kind of charcoal filter are nice they put a heavy dent in the chlorine taste.
The best packable (these are tiny) BOB filter I have found are the Aquamira frontier filters. They have a "Pro" and "Regular" model. I don't consider the katadyne pocket or the MSR Pump to be in the same league but they are also are not in the same weight class. These described are for extremely lightweight carry and all can be stuffed into a nalgene (which could still hold a few things i.e. firesteel, Mylar blanket, mirror, compass, 25ft hank 550 etc. with still even pry a bit more room for some other small things and that's all in a nalgene bottle.) a normal water filter is about the size of a nalgene bottle for reference. So these are truly BOB filters. The other larger filters (MSR / Katadyne) fall into more of an expedition class and that's a whole other bag idea than a bob.
Ill start with the pro. The Frontier Pro (military version) is a small filter it looks like an camelbak inline but is smaller around. It filters right at 50 gallons +- it is disposable (normal retail is 25.00). Here are the cool parts it clicks into pretty much any bladder there is whether it be camelbak, source, or platypus bladder. It fits all 28mm bottles (think ozarka bottle or 2liter coke bottle etc). It can also be used as a high capacity survival straw (its little brother the Frontier filter filters 10 gallons vs the 50 of the pro). It is also possible to use it as a drip filter to filter water while you are away or sleeping or busy.
The Frontier Filter (regular) filters right at 10 gallons +- its the size of a lipstick tube maybe a bit thinner and is disposable they retail normally for 12 bucks. I keep one of these and a pack of 10 chlorine tabs around no matter what, takes up the space of a pack of cards. These are great little filters in a pinch you can drink out of a source (without chem treatment) and at least know you wont get any cysts or other bacteria but there is still a chance for viruses better than nothing though especially in a high paced setting or on the run etc.
As far as getting tabs Aquamira and katadyne both make good ones. I like the Aquamira military tabs they are packaged better (more usable on the trail) and come in sets of 10 or 50 and treat 1 tab = 1 liter. The Aquamiras also fizz like an alkazeltor and spread around the chemical on its own. There are also a few liquid options offered (drops) Aquamira makes one I prefer that is in two solutions there is another company that I haven't seen in a while that made one that didn't need mixing cant remember who now though.
As a shameless plug my company does sell Frontier filters and Treatment Tabs and you are welcome to pm me for more info and a discount if you would like.