I work on a lot of blowers at my shop, Echo, Tanaka, Stihl, Redmax. Most of our commercial customers who do not already own Stihl are switching to Stihl when a repair is not worth fixing.
Echo, Stihl, and Redmax seem to be the most popular.
Echo's have several backpack blowers. The cheapest versions use the same handheld motor( throw it on a frame and add straps) Not the best especially when the echo blowers have a tendancy to get carbon buildup in the exhaust port. Even the newer Echo blowers don't seem to hold up as good as their old blowers.
Redmax seems to hold up ok. I replace a lot of crank seals and carbs on these models. Mostly because the fuel these guys use.
Stihl seems to be the easiest to work on for me. The new 4 mix blowers have the problems worked out, they are lighter, faster, larger volume of air, and cheaper to run. Problems are usually things physically breaking(frame, straps, nozzle's) Usually adjusting the valve clearances fixes most of my problems.