I have run a cleaning business for 30 years. I have had the opportunity to use a large number of different vacuum cleaners. Although I have never used a Dyson, I can say that all the rest of the bagless vacuums are a total pain in the @ss. They can take hours to properly clean and service, and some of them have costly filters to replace as well. Although the bag vacuums do decrease in suction as they fill, in my experience, they are still easier to use because maintenance mostly consists of replacing a bag.
I prefer vacuums that are easy to unclog myself. Some of them require a trip to the shop if you get a clog in the hose. ThereforeI want a hose that is wide enough and simple enough that I can run a broom stick down it to help unclog it. It also means I want as few extra bells and whistles as possible, because there are less to break.
I used to have a Kirby. It was great. It had a motor that never burnt out, it had a hose that rarely got plugged, and when it did you could unplug it yourself because you could run a broom handle through it from one end to the other. It also had tons of cool attachments. Replacement parts were not expensive, and it ran forever. However, it cost a fortune, and unless you are anal retentive enough to save your receipt for 15 years until it needs factory service, you can forget about getting it repaired. Because they will not help you without proof of purchase, Kirbys are a bad choice in my opinion.
When my Kirby died, I bought a simple, no bells and whistles vacuum. It was the cheapest on the market but it fit (almost) all my requirements. Here’s a link to the one I bought, http://www.google.com/url?sa=t&source=productsearch&cd=1&ved=0CEkQgwgwAA&url=http%3A%2F%2Fwww.newegg.com%2FProduct%2FProduct.aspx%3FItem%3DN82E16896200210%26nm_mc%3DOTC-Froogle%26cm_mmc%3DOTC-Froogle- What I did not like about this was the fact that it did not do bare floors so well, and the beater bar continues to run if you are using the attachments. I bought mine from a local dealer, but it can be bought online.
and here’s a link to the cannister varriety. http://www.generalhouseware.com/Vacuum_Cleaner/Vacuum_Cleaner_47.html I did read a review that the bags are hard to find, but I would imagine that if they sell the vacuum, they should sell the bags too.