It was hard for me to choose which Sonic game was going to make my list. The first game in the series I owned was Sonic the Hedgehog 2. It had come as a pack in with my Genesis model 2. Sonic 3 had a lot of cool features and was visually impressive, but I hadn't spent as much play time with it as I did the first two titles. In the end it came down to the most important factor. What game was the most fun. For me it was the Original Sonic the Hedgehog.
I never owned this game during my childhood, but one of my best friends did. I'm sure that is where a lot of us have our best gaming memories. Late night sleep overs and after school couch sessions at a good friends house. We played this game taking turns at my friends house. He also let me barrow it for an extended period of time on more than one occasion.
I think I fell in love with this because it was very colorful and fast paced with a memorable sound track. It seems to be the most colorful in the series. I love the parallax scrolling backgrounds. Stage one's background looks so distant, yet detailed, and lively. The game play was fun and the stages felt like they were built around obstacles and unique enemies, where as the sequels tried to push the visual factor, speed, and zany loops and pipes.
If anything can ring in the feeling of gaming nostalgia it got to be that famous "S-E-G-A.." chime, played as you booted up the game.
I was never really good at the Sonic games, and I'm not sure I've beaten any of them without cheating. The great thing about these games though is the difficulty is very balanced. I could make it very far into these games before calling it quits. I really liked how they handled the characters life. You collect rings. When you get hit your rings go flying every where and you have a chance to grab a few before they go bouncing off the screen. as long as you can keep control of at least one ring you'll manage to stay alive, unless of course you fall into a pit, then it's instant death.
I'm sure a lot of people would have a Sonic game higher on their list. They are great games, but I just had more fun with other titles. The Genesis certainly had a great library of games, so it's no knock on Sonic.