My '14 Mazda 6 D has the best gearchange of any car I've ever had. Provided it has the right oil!
I know this because when I had some major work done and the transmission was removed and refitted, the wrong oil was used in error. The result - crunch, crunch, takes three attempts to coax it in. I returned it to the dealer and moaned, they drained and replaced the oil with the correct stuff, and, hey presto, the gearchange is like flicking a switch again. Anecdotally, MX-5's are also very susceptible to this. I don't know the specific grades of oil, but I daresay I can find out if anyone is interested...