I've got a HOT (Hang On Tank) Magnum canister filter that came with a 38-gallon setup my wife purchased a few years ago. Reliable, and it's on a timer for a 1/2-hour shutdown twice daily so that the autofeeder can do its thing. The water polishing pleated filter does a great job, and there's room for media bags if you don't use the bonded filter sleeve (prefilter). Hasn't given me any problems, ever. The pleated filters are easy to clean, though I've got two for this setup to enable quick swaps.
The Magnum 350 may not be the most elegant-looking design out there, but I've got two of them, and am quite happy with their reliability and low operating noise. Both are on a timer as well for autofeeding.
I've got one Magnum 350 pulling strong through all 4 UGF plates on my 100-gallon tank (that's mine, not the missus') through a manifold I rigged to link all 4 plates, all of this submerged under a few inches of small-medium gravel, and it feeds to an outlet and a large biowheel. I considered drilling, but it's an old used tank, and I didn't know if the bottom was tempered or not. 4 holes linked to an under-tank manifold would have been ideal. This particular Magnum 350 came with that old tank, and I think it had about 10 years of service before I purchased it. After replacing a worn impeller magnet assembly, I was off to the races. By the way, that magnet got chewed up because the previous owner had allowed gravel to get into the sump housing (how he did that I do not know, unless the filter was not in place). Otherwise, it's a great, relatively inexpensive setup.
The second Magnum 350 takes care of water polishing, only (along with any media bags I toss into the housing outside of the pleated filter and its prefilter sleeve...the housing is roomy). It pulls through a sponge originally built for a reverse flow kit as a prefilter. Almost done rigging the Hydor 300-watt inline heater (haven't needed it yet) and a Fluval surface skimmer. I was going to connect it to the same UGF manifold, but that other Magnum 350 is doing a fine job all by itself. I've only run this newer one for a couple months, now, but if it's anything like it's older brother, it should last for the next decade.
The Magnum 350 has only one moving part: the impeller. Like the HOT Magnum, I've got a spare pleated filter for each to enable quick filter changes.
Petsolutions has a sale on them, the basic filter going for $74.99 U.S. That's one of the best prices I've seen. The Deluxe setup, with cutoff valves, goes for $79.99, and the Pro, w/ valving and biowheels, is just $5 more.
In short, to answer your question, a quality canister, with proper periodic maintenance to the filter elements/media, should last as long as a well-built car. B)
i had a Pennplax canister filter that worked well for over a year. Pennplax was good enough to replace it under warranty. eventually it became nearly impossible to get it to start working. also the gaskets needed replacement every time it became hard to reassemble. that's just my own experience. i'm sure canisters work well for people. my own experience was it lasted slightly more than 2 years. however i was using it for a turtle tank. as we know turtles are quite messy and maybe the frequent water changes were too wearing on the particular canister - Pennplax 1000.How long do How long do Eheim ecco External Canister Filter 2232 last?