Well thats news to me, i thought mario kart was easier after mario kart ds really
as for control ease, i like the way mario kart wii is there, i have a much easier time playing that game with a wii remote+nunchuck (or whatever its called), i also like the auto drift option which was much easier on my hands than having to hold the R button or whatever it was on mario kart ds just to turn easier, that got tiring at times.... Im very petite regarding my physique so my hands are rather small and as such, having to hold that button for every turn is much uncomfortable for me so i was very pleased with the auto drift feature on mkwii.
Aside from controls and comfort issues, i still find myself pleased more with the available items in mario kart wii compared to everything before that, +the graphics its one of my favorite mario kart games ever. Even mario kart 7 didn't surpass how pleased i was with mkwii!
So, in short, mario kart wii is probably easiest for me at this point, especially regarding comfort issues with the controls!