I think that Beyond Oasis was awesome, it was the Genesis' Link to the Past in my opinion. From the Steam's collection I would pick up Gunstar Heroes, Streets of Rage 2, Golden Axe II, Sonic 3 and Knuckles, Vectorman and Comix Zone. It'd be nice if they had Jurassic Park, Robocop VS The Terminator, Road Rash II and General Chaos as well, there were so many other good games on the Sega Genesis, good times.
Fortunately I don't have to buy a single one of them since I own about 40+ Genesis titles, although I don't play them regularly, I still play some every now and then, and when I do it usually doesn't last very long, I tend to get bored fast with them so I try not to push it too much, I just play about one or two hours maximum and I don't play any of them for a week or two. It was awesome back in the days however, of course, I could stay up all night and play games on my Genesis, well in fact I did, many times, and I don't regret it one bit.