best artists in the last 15 years

That's a lot of territory to cover -- You're going back to 1993. You might be more specific about who you like from before 1993 and then we could recommend similar artists.

In jazz, I think there are the biggies: Diana Krall, Brad Mehldau, Christian McBride,

I'll take exception to your slam on Diana Krall. I loved the music first. In fact, I take some pride that while I was searching for my first pair of high-end speakers in LA back in 1997 or so, more often than not when I'd play the Diana Krall the staff would ask me who she was, and upon further visits I often found that they had bought the same CD that I had brought in...

So, at least in my case, I think I helped Diana Krall become an audiophile favorite BECAUSE I LIKED THE MUSIC, not the other way around.

Besides, someone had to replace Jazz at the Pawnshop and that first Fourplay CD that everyone was demoing....