The Newest Types Of Generators Denyo Portable Petrol Generator ?

Portable petrol generator ? - the newest types of generators denyo

I buy) a generator (new or 2nd hand and I wonder if anyone can advise me on certain issues.
(a) What is the advantage of the "investor" generators.
(b) The advantages and disadvantages of 2-4-stroke.
(c) any brand and type that you recommend.
(d) What is the sound / s (I will not disturb the neighbors)
My budget is limited to approx € 150 - € 200.
Thanks for any help or advice.