First RV for full timing: Used or New?

If you can afford it, RENT a unit for a few weeks, to a month, see how you like it, size, amenities, ETC. Then rent another larger or smaller one, do the same thing, compare notes. YOU WILL NEVER FIND THE IDEAL UNIT. All have strong points, and weak points, Just as your house has. If you can, go to one of the larger RV shows, that way you will have an idea as to what direction, in size and options you require.
But renting a unit is cheeper than buying, then trying to sell it as you change your needs. We all have moved up or down in RV units and sizes.