When I was younger, in my house, we used to have a Super Nintendo and a Megadrive. I could only ever have one set up at a time because of the one television in my room. In general, I prefered the Megadrive.

Although these days, I'm very much a GameCube > Playstation 2 > X-Box person, I still consider Sega as a company very capable of producing quality games, for their own consoles (Megadrive and Dreamcast in particular) or others (the Gamecube, for example).

As Joel pointed out in his post, Sega have a number of games series (serii?) that have been very enjoyable in the past. Now, while I openly admit, I much prefer the 2D Sonic games to the 3D ones (though the 3D ones were quite fun, just not to the same extent), Sega are quite capable of producing even now.

I'm not sure if it was made by Sega or not, I believe it was however, but Shenmue was a very enjoyable adventure game on the Dreamcast, and I'm still disappointed that I've never been able to play the sequel after I enjoyed the original so much.