I have 3 Sega Genesis 2's, and a Sega Genesis 3. I unfortunately don't have a Sega Master System, but that would be a fine addition to my collection. For the Genesis I have Sonic the Hedgehog 1 and 2 and Sonic Spinball, and i'm hoping to further my collection. I also have Sonic 2, Sonic Spinball, and Robotnik's Mean Bean Machine for the Sega Game Gear. I'm also currently on the look out for games like Alex Kidd and the Golden Axe Series(I loved those games as well) I'm also hoping to find a copy of Comix Zone for the Genesis. That game had amazing music, vibrant colors, and surprising gameplay for it's time. I'm also looking for Phantasy Star games, and I also have a Sega Dreamcast with Sonic Adventure.
You seem to have a great collection going on right now, and i'm jealous of your progress. I hope for my collection to become that good at least some day.