The Megadrive is my most wanted by a long chalk, awesome machine.
Monk - If you're judging the Megadrive on games like Buck Rogers and Road Rash then you're bound to be unimpressed. Try Golden Axe, Streets of Rage/Bare Knuckle, Shining in the Darkness, Shining Force 1 + 2, Langrisser/Warsong, Gunstar Heroes, Dynamite Headdy, Contra: Hard Corps, Alien Soldier, Hellfire, Zero Wing, Magical Flying Hat Turbo Adventure, Strider, Atomic RoboKid, Aero Blasters, Axis: Final Zone, Ghouls N Ghosts, Devil Crash, ESWAT, Revenge of Shinobi, Castlevania: Bloodlines/New Generation, Alien Storm and Wardner. These are just a handful of the games I love on the MD. Top machine and I really hope it becomes emulated on the GP32 one day.
On the subject of the Amiga, as several people have pointed out, someone who is only 17 years old simply cannot comment. The machine was MASSIVE (largely thanks to piracy, but there you go) and I remember wasting many hours away on it. Anyone below the age of 20 would have still been in nappies when the Amiga was strutting it's stuff, so keep your mouth closed next time you feel you have to comment on something that you know nothing about.
Kitsune - I thought it was too good to be true. Since I've been on this board I've been really impressed with how friendly everyone is, yet you manage to spoil it.