So I'd like to start off by saying that I don't care much for the story when it comes to a fighting game. So I'd like to focus on the mechanics of the gameplay first and foremost.
From the start, the theme music is much to my liking. You can watch it here
Regarding the characters, there are a lot of different types. You have your standard Ken, Ryu, and Chun-li, but in the 3 series, Capcom introduces fighters out of the blue. For example you have my favorite:
And some other fun characters:
When the fights start some fighters have certain intros when you fight another certain character. For example in this video, Capcom has a pun where if you fight Alex vs Hugo, it''s like Andre the Giant fighting Hulk Hogan:
It's a smooth game where there's not too much craziness going on while you are fighting. They have standard grabs, Anti-Airs, and specials. However, the one thing they have that makes this one of my favorite games is the parrying system. Basically, if someone attacks you, you can hit forward on the stick at the exact same time (or down if it is a low attack) to counter there attack which allows you to follow up with your own combo while you take no damage. Some people thought this required no skill and so it was not used in the later editions. In my opinion, it requires a lot of skill to predict what your opponent is going to do and allows for an unpredicted match. This is the best example as to why the parrying system is so badass.
Overall, this is a great game and I recommend any fight game lovers to try it out!