See this thread at GWeb Appliance forum.

My builder gave us a Dirt Devil Pro Series 990 central vac system with the Edge powerhead cleaning kit and I absolutely love it. I was very leary of a Dirt Devil unit becaues their residential uprights & canisters are terrible in terms of quality. However, their central vac systems are made by HP who also makes Vacuflo units. Granted, mine isn't a true cyclonic system as there is a filter cartridge which must be replaced annually for about $25. However, even after 8 months of HARD use, I haven't noticed a decrease in suction at all. I have emptied the canister twice..which isn't fun...but neither was emptying my old Dyson everytime I cleaned. I'd install one again with no reservations. My parents have a ten year old MD Silentmaster central vac system that they love as well. Definitely choose a power unit that is sized for a home larger than yours and invest in an electric powerhead. I'm having a HAH outlet installed in my kitchen to tackle all the wood floors on the main level of my home but would be at a loss without the Edge powerhead. Good luck!

Thank u!! I think I am going with hide a hose. Any opinions on which unit to go with the Best and most powerful?

Instead of spinning your wheels to figure out the best, I'd first find an authorized HAH dealer/installer and go from there. Mine is a Vacumaid. It's cyclonic and vents to the exterior. Is it the best? No clue as this has been my only experience with a CV. I trusted my installer to size it correctly and I feel confident he did. It has been great for my needs, but I don't need or use a power head with it because we have all hard floors. We once had a plush rug on which I used the Turbocat. Hated the Turbocat and never felt like it did any better than the carpet attachment (just a wide smooth head with no beater bar). My Vacumaid has so much suction, I can't really see how a beater bar would be that much better. If it is better, I suspect it's marginally so. Even if I had carpeting, I'd choose the HAH over having to have the electric power head. I'm able to get all the dog hair off my rugs without the beater bar, so I'm happy with it. :)