It amazes me how tire threads and "oil threads" are similar: Never ending personal "opinions".
I agree that the Michelin tires are "quite good" (but, NOT perfect at all either), and I disagree that the Kenda tires are that bad to have to be taken off after 400 miles. That's "personal preference", not more.
I went with all my motorcycles and scooters through about 200 tires so far, 65% of that are rear tires, 35% front.
I had only two tires that I absolutely hated, or, did a very lousey performance (wear), and I am not naming the brands, because it was apparently a "screwed up model", or production run of a tire they produced. Actually one manufacturer gave me a FREE new "other tire", (different model) and it was fine.
So, do not be totally discouraged by lower price in regards to grip, however "usually" the more expensive tires do have less issues with "wobble" as they are more precisely manufactured (not only top to bottom = "static balance", but also side-to-side evenness = dynamic balance = related to handlebar shake, exactly what we are discussing here. Right?!
So, leaving all personal "Opinions" behind, IF your local scooter/motorcycle shop has an electronic balancer where they see the "dynamic values" and also can correct them, then you should work with them all the way through rather than buying "cheap" some grey market second/third quality tire on-line.... You (can quite often) get what you payed for, good or bad... either way.