Pick a more 'mature' artist who you consider to be top of their game. Argue the toss over whether any young pretenders are (or have the potential to be) better than the 'mature' artist CURRENTLY is.

My pick - Aphex Twin - 43 now, top of his game throughout his career and still relevant.

I would say Kevin Shields as well (but I don't think he pushed the guitar forward with mbv as much as he could have done).