I am one who advocates a 4ch trainer style plane. I used to teach many to fly years ago and 3ch was not my preferred choice.
But go-it-alone ... you need a forgiving plane and that means high-wing with a touch of dihedral. Good wing area and preferably not tapered. 4ch - yes even though others will say dihedral and ailerons do not go together - that's rubbish as long as dihedral is not excessive.
Most trainers in 3ch guise tend to wallow around and will not handle wind / gusts as well as a 4ch machine.