Hey guys, thought I'd chime in since its football
The LT/AD (yes its "AD" b/c his teammates have always said he can run All Day) fantasy debate is more so about league settings and team dynamics than pure ability. As Sulman already stated, in a league that gives you points per reception, LT should be the obvious choice, though the Vikings have claimed to start getting Adrian the ball out of the backfield more. The injury concern is also a huge one with not only Adrian, but all running backs...durability through 16 games is a lot to ask of any starter in the NFL. Adrian's upright running style definitely does leave him in the open for injury, but it also tends to roll tacklers over and get him insane yards after contact.
I honestly think the most important part of this discussion has to be the talent surrounding the players on offense. I'm as big an AD fan as they come, especially considering he went to OU, but Tarvaris Jackson straight up can't cut it. SD has a solid QB in Rivers, and the best TE in the game in Gates, so they can tend to keep defenses honest. Peterson on the other hand will face 8 men in the box all day long, and that is the reason he tends to have games where he is shut down. You put enough ppl in the box and any RB will be shut down, but its the passing game's responsibility to keep a defense honest.
Either way, you can't go wrong with these two...head says LT, heart says AD