Depends on to whom you listen.
Seriously, you may get a thousand different upinions even on here, the most reasonable, well behaved forum of all forums!
It was determined long ago (2004) that Kymco instructions were confusing but the result was most all models work just fine on USA 87 octane rating (R + M)/2 ordnary pump gas available anywhere in the USA. Regular non-ethanol works the best but usually way more expensive.
We have used both in our Kymcos since 2004 with excellent results and no drawbacks. Models include Agility 50, Yager 200i, People GTi300, Downtown 300i and UXV 500i.