I am in the same boat as you and am looking closely at the Husq 570, & Echo 770. I am leaning strongly towards the Husq 570BTS as it fits me well, I like the air filter better, the straps make the unit fit better and it has enough MPH/CFM to move my 2-3' deep piles of leaves.
I eliminated the Stihl, as I spoke with 2 of my local dealers and both said "Yes, you will need to do a valve adjustment at some point". So it is off my list.....
After trying on both, I think the Husq is more comfortable, and the beast of a filter that is easy to change out give it a leg up in my opinion for my needs.
I will be buying on in the next 10 days as the leaves are starting to fall!