I'd have to agree with most on here that say Sonic has fallen pretty far from those days of glory, what was once a glorious 2D platformer quickly deteriorated into a derivative, unplayable (in the case of the PS3 and Xbox 360 "Sonic the Hedgehog") 3D mess. I have been totally disappointed with every 3D incarnation of Sonic and, to be honest, I don't honestly believe we will ever see the Hedgehog at his greatest whilst in 3D.
A few others, Banjo Kazooie: Nuts and Bolts, if that turns out to be half as good as Banjo Tooie, I will eat my hat. Gone are the simple platforming joys and instead we are left with a vehicle system which, frankly, has no place in the Banjo universe.
Also Crash Bandicoot had a fantastic first 3 games, I still think Crash 3 is one of my favourite games of all time. Yet now we have these Crash of the Titans and whatever the next one is incarnations.
Boy, reading this you'd think the Platforming genre was in dire need of a saviour.