Amsoil Saber in my Stihl trimmers, blowers, and chain saw. I mix the Saber at the Stihl recommended 50:1 ratio.
We have non-ethanol 91 fuel here, which all my outdoor power equipment gets.
As I draw close to the end of the season (a month or so out), I begin to use fuel stabilizer as well to ensure proper distribution through the entire fuel system.
When the equipment is finally put away for the season, I unscrew the spark plugs and give them all a shot of fogging oil.