Individual contests reward your top performers. Team contests build accountability and pull your newer reps up. The best programs use both.
When to go individual
Use individual contests when you want to surface and reward your closers, or when reps work mostly on their own accounts. The recognition is personal and direct.
When to go team
Use teams when you want your veterans coaching the new reps, or when you want to lift the whole floor rather than one star. Nobody wants to be the reason their team lost.
Run both at once
Score an individual leaderboard and a team standings from the same data. Reps compete for themselves and for their team in the same week, which doubles the reasons to push.