Joint 1st: Greenland and British Columbia (islands and mountains near Vancouver).
Thereafter, selecting the order becomes more difficult but I'd include:
New Zealand, the Western Cape, Botswana, Great Barrier Reef & the Sunshine Coast (QLD), Ayers Rock/Uluru, Colorado, the California coastline, French/Swiss Alps and probably the Florida Keys and the Caribbean although the last two fall short of the others in variety of spectacular scenery.
and how easy it is to get checked out and rent aircraft
Still relatively easy in the US.
I don't know about the other countries because I was very happy to fly with either a Flight Instructor or a local pilot.