Well, when my brother took lessons from Gene Krupa and Cozy Cole in NYC at their studio in the late 1950's, they said that at 16, he was much better than either of them were at that age. Unfortunately, college and a degree in Theoretical Nuclear Physics called, so he quit. They did carry him out to the 50-yard-line when Queen Elizabeth came to his college (William & Mary) his freshman year so he could play a solo with the marching band at half-time. (Yes, I have photographs for those non-believers out there.)
But I digress. Don Henley plays and SINGS at the same time. If you think THAT is easy, TRY IT. As far as Ringo, well, he was amazing at what he did with the Beatles, but greatest of all time? I have no idea. Playing drums is a skill that takes years of practice. Bashing out slams on skins doesn't make one a drummer/percussionist. Drummers and bass players make rock music rock, so I would say anyone who fits the band and music is pretty darn good. Watts was amazing at "driving" the Stones style and making it special, but so was James Brown's various drummers, so...pick your poison, I guess.
Best Rock Drummers
I've seen most of them and by far the two that stand out are Neil Peart of Rush and Ceasar Z. of Golden Earring. For non-rock I would say it's a no brainer with Buddy Rich.