Quickie had some real trouble with motors for awhile. Mainly stripping the shafts. I have not heard of this happening in over a year.
I have had great luck with all the Invacare's through the years, but some of the ad-on specialized seating and controls have been garbage. For a good basic chair I do like Invacare, for more specialized the 21st Century Bounder H-frame is the way to go especially if you want power and speed.
I hate Electric Mobility Rascals with a passion. I did some work with them years ago and now I refuse to even let them in my shop. The equipment itself is OK, nothing great but OK. The problem is the company lying to customers, pushy sales people, etc.