Assuming the Warriors stay located in the seven hole, and assuming Anthony Davis doesn't fall six spots, there is no guy the Warriors "MUST" draft—rather a short list of instant impact guys the Warriors should consider.
I don't want to over-hype the 2012 NBA draft out of fear of applying added pressure to the Golden State Warriors management, but this could be the most important draft since 2001 and likely could have the greatest impact as the Warriors rebuild for a move to San Francisco.
This upcoming draft is deep because of the recent sophomores who opted to return to school when the NBA was in flux during labor talks last summer. Therefore, with the Warriors having four draft picks, they can obtain a solid cast of players even in the second round.
All that said though, it starts with the seventh overall pick where the Warriors cannot afford another missed opportunity. If available, the Warriors should draft Harrison Barnes out of the University of North Carolina, as he seems to be the ideal fit for multiple reasons.