I don't have either, but plan on getting BF3.
Based on discussion with one of the Sergeants in my unit who has seen combat first hand as an 82nd Airborne Division soldier, he said that BF3 is "real enough to make me feel uncomfortable, like I'm back in it." If that isn't an indicator of how real a game can seem, then I don't know what is!
'11 BMW E92 ///M3 - ZCP and DCT
'15 Ford F-250 - Lariat, 6.7 Powerstroke Turbo-diesel