Well, we sell ECHO now where I work, and they USED to sell stihl along side ECHO...but that arrangement ended some years back. Too many problems with Stihl equipment, upset customers, long waits for parts, repairs are excessively expensive, etc..
I love my 1 year old SRM-210, and my 6 year old CS-520 echo saw.
IVe found, having been repairing handheld equipment professionally for over 5 years now, that Stihl is the hyped up brand in the small engine world. It's like Lexus...people who spend big $$ on them of course are going to say they are the best ever...but the people that work on them know better.
Stihl saws are heavy, overly complicated, difficult to repair, and have "special" parts you can only get from a dealer, like accordian fuel lines, grommets, filters, etc. The air filtration sucks.
The trimmers are odd, they have a tinny rattle sound to them, are pretty loud, melted plastics are common, the hardware is TORX headed bolts...so when the heads inevitably strip...you are SOL. The feel to them is harsh.
Echo designed products are more durable on the outside, and inside. They dont come in all beat to **** and broken up like the stihls seem to...so often.
Echo offers a great, simple, yet durable split book design...pull the tab up, turn the knob and it slides off.
Furthermore, you arent going to beat ECHO air filtration, on any equipment, bar none.