TurboGrafx-16

TurboGrafx 16
Even though it was not very successful in the West, the TurboGrafx-16 (or the PC Engine) was very popular in Japan. It had many variations and add-ons, most notably the TurboGrafx CD. HuCard converters are somewhat hard to come by and can be expensive, so you'll definitely want to region mod so you can enjoy all of the many, many, different versions of games via region and region exclusive titles. Also this system is home to many, many beautiful games with beautiful soundtracks and very impressive specs for its time! If you like shoot 'em ups this is the system for you.

The TurboGrafx was succeeded by the SuperGrafx... well, at least that was the idea, but it was such a flop that it died out before the TurboGrafx.

Variations
If you want to play CD games, the TurboDuo is the system to get; it is the console, the CD drive, and the Super System BIOS, as a single device. Of course, if you have the regular TurboGrafx, you can get the other parts separately. Now, if you want a badass handheld, the TurboExpress is a nice choice.

[* means the game is also available on the Turbo CD]