When we bought Jewels' MS211, they had a deal where they'd give you a Stihl filing guide sharpener if you bought a pack of Stihl synthetic oil. Seemed like a no-brianer.
Ethanol free 87 from the Gulf station near the house with Sta-Bil, I keep a couple 5 gallon Jerrycans of that for the mower and generator. I even pump that same ethanol free in my Grand Marquis and Jeeps. I use synthetic Sthil oil and Jerrycans to make 50:1, 1 gallon at a time. All was good for a couple years running that.
I got a Homelite leaf blower years ago that came with some premix oil. I put those bottles on the shelf with the other oil. Came time to mix some more 2 stroke gas, for whatever reason I grabbed a bottle of that 2 stroke oil that came with the Homelite instead of that Stihl synthetic. I was cleaning fouled plugs on both saws about every 20-30 minutes with that garbage. Went back to the Stihl 2 stroke oil, and no more issues.
I've bought a can of Truefuel in a pinch, but it's silly expensive as many others have already pointed out. I'm still in the mix my own camp.