...I'll kick it off by saying I have so many but my favorite of the more recent players is Adam Steffey. So smooth and fluid with impeccable technique and taste. Such a monster player, singer, writer, and arranger. He's my current #1. Sierra Hull is nipping at Adam's heels IMHO with a very similar, perhaps Adam-influenced, style.
Of the old school players, Herschel Sizemore just never ceases to blow me away. For the same reasons as those listed above for Adam and Sierra but with an
"old school" style. Ronnie McCoury is another with the "magic touch" and always says it...just right. Someone you don't see or hear much of that is another mandolin juggernaut is Don Wayne Reno. Great, great, player. OK...your turn.