Lupe's flow is always good, throughout the song, and in terms of lyrics, there's no comparison to any other rapper.
Weezy's raps focus on punchlines, and that's it. They're usually dope, but the rest of the lyrics are stereotypically mainstream.
The Game's lyrics/flow really impresses me, however, I don't really like his representation, in terms of what he raps about. However, "My Life" is great.