Genesis was a nice system. Though, it lacked in some areas with it's competition (TG-16, SNES) it had some advantages in other areas and was able to hodl it's own pretty well. I've had no issues with the system, other than at times the speech is a bit garbled.
Each of the Genesis systems ahd their pros and cons. As a stand alone unit, the Genesis 1 is nice, Headphone jack is always welcome. For combining with a Sega CD, if it's a bottom loader, yeah, Genesis 1. If it is the top loader, gotta have the genesis 2. Still, if I'm hooking up a Sega CD, I'd rather have an X'Eye so I have one less AC Adapter plugged in.
The Genesis 1 model Doesn't support stereo through it's A/V jack, though it supports it from the headphone out (I think...) Genesis 2 the stereo is through the A/V cable.