Don't forget about the weight of the saw. My son-in-law bought a Stihl which is just a PITA because it is so damn heavy compared to my Echo. I have a Stihl backpack blower and the top of the line FS131 string trimmer and they are great. However, so is my Echo chainsaw. Been going strong for over 15 years! My Echo will take 16" - 20" chain bars and it is 10.8 lbs. The Stihl MS170 clocks in even lighter at 8.6 lbs.
I find a 20" chain bar preferable to a 16" one. However, to step up to a 20" bar in Stihl you have to go to the MS-271 Farm Boss which will set you back $430. The Echo CS-590 Timber Wolf will take 18", 20" and 24" bars and will set you back $399 - $419.