Forget the 2-strokes.
bite the $$$ bullet and get one with a 4-stroke Honda engine (even the Chinese copy Honda), start (almost) first time, every time and no need for mixing oil and petrol.
We gave up long ago on the "auto-feed" heads, they either don't feed at all or feed out half a mile, we now use a simple head with 2 or 4 cut lengths of string, less wasteful of both string and time.
We actually have two. Our first lasted 10 years before it became difficult to start, so I bought another whilst re-building the earlier one. It turned out that the starting issue was the electronic magneto, easy fix (parts from the local farm shop).