In my experience they vary a lot. Cheapest is the US with zero landing fees,
AFAIK this applies to all airports, no matter the size (been a while since I flew into a major airport there, but don't think it changed).
In Europe, the difference between small fields and big airports ranges from non-existent (Spain - they all are about EUR 11 or so), to vast (Austria, where you can easily drop EUR 60 at the majors, as they charge an 'approach fee' even if landing VFR).
For hour building, there's really only one country - the US. No landing fees and a/c rental at about half the price of Europe.
