Neo Geo CD.
AES/MVS is the most talked about Neo Geo Systems. The CD just took those games and made them cheaper and easier to get for the most part. Sure it had load time issues. Only using I believe was a 1X rom drive. I think Saturn and PSone used 2X. However those systems also had 3D games while the CD was just porting the AES/MVS games. So was a bit frustrating. Still because the games are cheaper at about 50$ as opposed to 200-300$ for the carts. One nice thing I liked is for people who preferred a controller over an arcade stick they included that as well but had no dpad. It had what looked like an analog stick but really was a mini swither arcade stick for the thumb. They also used this on the Neo Geo Hand Helds. The system still worked with the arcade sticks.It did have a few exclusives in KoF 96 and SS RPG. The main selling point is price and today for collectors who are not smoking 100$ bills it's still the cheaper option. It's not super cheap either but no one ever said collecting was cheap.
Got mine with a couple of games, boxed with all cables and instructions for £120. Ignore what people say about load times, they're not that long, no different to a system of today. Games aren't that expensive either, prices start from around £15. And yes, the pads with the little sticks are awesome.