Prefer the first installment. FEAR 2 has its "@#$%" scare moments, but not as foreboding as the FEAR 1. FEAR 1 wins combat/weapons-wise, due to weapons tactics. (I miss the CQB melee of FEAR 1. Power Armor Suit in FEAR 2 is gimmicky)
But FEAR 2 does have better AI and two of the levels had me going "Enough with the spawning already!"