You killed the thread by not posting another choice to make Rohan!
So I will temporarily reverse ninja the last two choices and say Sonic 3, due to the fact that we could play 2 Player and make it way more difficult than it has to be.. (and yes, from my recollection all the games with Knuckles in them seemed to be easier for some reason.)
&& 256 color sprites, because I used to think NES was the best, but that was only before I got my hands on a SNES, and then that trend continued until I got involved in graphical representation stuff that was so detailed that someone wouldn't even be able to tell the difference between the real pictures and the falsified ones, even if the program was interactive.
(still going to just wait on Rohan to post the next choices.)