I've played all three specs in great detail (switch up each week). My personal favorite is lethality, because of the mobility. Personally, MM snipers are an easy target for me, because I can Dot, Dot, LOS, Weaken Blast, LOS, Cull, LOS, Explosive probe, LOS, rifle shot, rifle shot, LOS, Cull, takedown (if needed).....dead MM.