Hey, maybe this could turn into a tire / oil thread but for gasoline: which brand is better, which really burns cleaner, which one my great- grandfather used for 2,000 years and never had any trouble, etc., etc., etc., ad nauseum. Good stuff!
Now that said, I have never noticed any difference in gasoline. I do not mean after using any particular one for 40 years, just tankful to tankful. One thing I did notice when traveling in the west, where pure gasoline is apparently still available (going by the lack of 'Fuel contains 10% Ethanol' tags on the pumps), I got more range on a tankful. Not all that much but still enough to be noticeable. Here in RI, all our fuel is laced with 10% ethanol... and I am not on a crusade against that either. For all the noise I have heard about how horrible the stuff is, I run it in everything I own from a string trimmers on up in engine size without any problems I am aware of. And I am not careful to drain fuel either; I just use whatever was in use last year; or in the case of the generator, several years ago when last test- ran. Now if possible, I do run carburetors dry on all small engines if they are equipped with a fuel shut- off but otherwise, no special attention to fuel age. And I never use any products like Dri- Gas (which is alcohol put into gasoline to make water miscible with gasoline..... exactly like the 10% ethanol already in our fuel).
We have a Citgo down the road from me. Believe it or not, I get better gas mileage from them. Don't use them very much, though.