>>11797716
Check out Jumping Flash on the PS1, yes it's in First Person but its a great game in it's own right, I also like Psycho Fox on the Master System or basically the same game Decap Attack for the Mega Drive. For modern stuff I'd be checking out the Spark The Electric Jester series (start with 1), La-Mulana (2 is easier to get into than 1 and more forgiving), and probably something in UFO 50.
I'm listing more modern games as you said you'd kinda blown through many of the retro platformers already.
Also Sonic 1 is my favourite in the series too.