I have 3, it is too close to call.
ESPN Baseball (PS2)
This game was one where I decided, I was going to play an entire full season. I think I got a third of the way into the season when the disc stopped working. It had taken some time to find it again. This was when PS2 was still current, so piles of sports games were not floating around for cheap like today. One of the things I like about this game is that you can switch teams at any point during the game. I do not like to pitch, so I could just bat for both teams. Roster management is pretty good, doesn't take up a ton of space on the memory card (although I did end up making a dedicated sports games memory card) and it was easy to start the season with the custom roster. I had made the custom roster a long time ago, it probably took 8-10 hours to do it.
NHL06 (Windows)
I loved playing EA Sports' NHL franchise. Tons of hours went into 2000, 2001, 2002 and 05. NHL06 came out at a magical time. The local team had changed their jerseys and was playing really good. And the modding community was able to bring more realism into the game. With the help of mods, I was able to update NHL06 so that it had the correct rosters, actual uniforms, actual ice surfaces and board, with ads and everything. One guy did a huge research project to find out what every team's goal, intermission and miscellaneous music played during gamees were and get that into the game. Then I learned to mod the game myself and ended up being the only person doing roster updates. It started to stink from them, doing rosters for a game mod is like a second job. You have to check and do the changes every day, even weekends. If you took a day or two off, you just doubled or tripled your workload. I eventually quit because you get to the point where you can't play the game anymore. It was still a blast!
Major League Manager (DOS)
This game was first released in 1986 and was re-released with updated rosters in 1989. It is pretty much all text based, has historical rosters and you can even create new teams and players. The coolest part was that you could just enter a player's stats into the game and it would figure out how good they were. No fiddling with speed/power/whatever ratings like modern games. I got this game around 1992 and have been playing it ever since! Recently I had made a new (updated/custom) version that took around 8 months of research and work. It is not 100% yet, so I haven't released it anywhere. This is by far my favorite sports game.
