I also had problems with my MSRs. Started with a sweet hyperflow due to how small it was. Unfortantly, it would need frequant backflushing even when trying to pump water out of the sink at home. I would be up a creek in the field with it. Next was a miniworks. Worked great about the first 3 or so liters my first time in the field with it. Clean and got about another 3 liters, took 3 cleans just to fill my MSR 10L Dromdery (SP?) bag. I also own a MSR MIOX which is a great little purifiying unit. I take it with me to travels thru out the world for work. Never been sick using it. Only down side... batteries are hard to find overseas, The smaller the grain of salt the more you need to refill it, and it takes time to work. Another thing MSR makes is the "siltstopper" I like to use it on ceramic filters as a prefilter. Small, light weight, replaceable elements, Im a fan. Last is their bags, the dromedary or whatever they are called. This things are TOUGH. I like them more than your average platty or soft canteen. Infact I use the 6liter as a bladder in my pack but only fill it about halfway, when I make camp I fill it up and use it as a pillow if needed, which act as a cooler on hot summer nights. The things take any abuse you can really toss at them. On long outtings like the hunts I take a 10L and shower kit as well. The things are really worth the weight in gold. They also make a lighterweight one but I have not tired them.
I also own a variaty of Katyden filters. I really like them but as with everything there is downsides. The hiker pro. Great little unit, and cheap. filters cost about as much as the unit when on sale, so the only one I had to replace I just bought a entire new unit on sale just before last summer. I keep one of these in each car since they can be bought on sale for about $50 every so often, keep your eyes open for GREAT prices on these. Also own a pocket, which ironically I have never seen a pocket on a person that can fit these, but they fit most pack pockets fine. The thing is my goto if anything bad were to happen and I had to leave in a hurry, its also the one I take on longer outtings. Almost complete SS construction has it weighing in like a lead bar, but still, if its durabilty your after, this thing is great.
Last is chemical purication.. I tried out "polar pure" this last year and have been impressed, its easy to use ready when you need it, "rumored" to last for more water than I will need for it. But being chemical you need to let the treated water sit after using, the bottle is just that a GLASS bottle, wish they made a nalgeen version for the bottle, and its temp senstive because of this glass bottle. But I still own 3 since they are so cheap.
My vote for cost/ durability/ easy of use... hiker pro.