My favourite sports game series is FIFA. The definitive and most up to date football simulator. Licensed teams, excellent in game sound track, yearly up dates to team rosters, improved graphics, added features/modes. I purchase a FIFA game once every two or three years.  I used to prefer Konami's International Superstar Soccer before it became Pro Evolution Soccer. The last generation has seen a huge decline in the quality of the Pro Evolution Soccer series with broken gameplay, limited features, unlicensed teams that need editing and the graphics look below the high standards set by the FIFA series. FIFA games over the last 4  years have scored around 10% more than PES games on metacritic/gamerankings. 

Anyway what is your favourite sports game series and why?

I hate all sports games, but I like Kinect Sports so I'll go with that.

Do the WWE games classify at sports games or fighting?

you can count them as a sports series. they can also be classed as a fighting game series. 

popular franchises gran turismo, forza, need for speed series are in their own category racing but they can be classed as sports games. 

I don't really care for most sports games that much but if I had Madden I would play that cause I kind of like it.

At first I was going to say Mario Tennis, but really my love of Mario Power Tennis alone is the reason for saying that. So I think for now I would go with WWE. Basically for a sport game to interest me on a level, it has to have some story driven nonsense. 

I bet if I could play the Inazuma Eleven series, that would be my favorite.

My favorite sport series is Top Spin. The main reason is because it's a great tennis series. I've played all 4 for them and love them all .

Mario. Wether it's golf, tennis or a mixture of several sports I find Ninty's games to be much more fun and have alot more charm than normal sports games.

NFL Fever was my favorite sport's series, but they cancelled it after 2004. If I had to name a current it would probably be Madden or Kinect Sports.

Racing is not a sport imo. If your not physical moving your whole body it shouldn't be considered a sport.

Mario Kart IMO > All other sports games combined. I know it is a very broad definition of the sports genre.