Trainer considerations:

What is the age of the student? 16 and under, 16 - 45, 45 - 65, 65 and up
What is their monetary ability?
Where are they going to fly? My field, private property, farm
Will they have an instructor?

I feel these questions come first and greatly influence the trainer type, size and capabilities.

But if you want to make a general case, an older guy who comes out to my field.

I recommend an ARF ( no attachment because they just spent 4 months building it).
Even a RTF.

The RTF Hobbistar 60 is the nearly perfect choice in many cases.
72" easy for old eyes. LA 65 nitro. Strong , easy, light and powerful. Full house a must. Radio is trainer (buddy box) ready.

I help anyone who comes out with something in hand already. But online I recommend a student answer these questions:
Where are you going to fly?
How are you going to learn (instructor on buddy box, videos, simulator, trial an error)?
What is your time availability?
How much money can you spend easily?

I give this because I think care needs to be taken to not put the cart before the horse!