Championship Manager is what Fifa Manager is today. So to me, there are 2 main manager games for you to choose from, Fifa Manager and Football Manager.
From my point of view,
Fifa Manager focuses more on visuals, nice graphics and nice user interface. They have pictures for a lot of players, even those in lower leagues. You get to watch a real match (played in Fifa style) instead of just watching a whole bunch of dots running around. However, the details of this game is disappointingly shallow. Skills and tactics don't really matter much in this game if you ask me though. The managers in the game doesn't use real manager names and the press is really stupid. Oh, you cannot scold your players when they're not performing well.
Football Manager, on the other hand, focuses lesser on the visual side (not so colourful la). You can say this game is almost the exact opposite of FifaM as Football Manager is very detailed in every aspect, to what I see la

Tactics are more important in this game compared to FifaM and the events that happen in this game is much more reasonable, if you know what I mean.
Overall, I would go for Football Manager (Imma get FM09 instead of FifaM09). Football Manager is the real manager game!!! EA Sports SUCKS!!!