Luxray and Electrivire should both run Physical sets since they have better Attack stats and better physical movepools. Ampharos should rarely be used though it has a monstrous Special Attack stat. (at 115, high in NU metagame standards) However, this will depend on what you are looking for, a physical or special tank. If you ask me, since I'm inclined to Physical, I'd go with Luxray. Luxray has Intimidate, which could be used as a cripple-sweeper. Electrivire is best used during Double battles. It can absorb a nice Discharge and speed up while it's ally Discharges the enemy to death. Note that if the opponent is a Ground-type, Electrivire will easily be able to cover that weakness. Ampharos is my favorite Electric special-sweeper from the NU, with a gigantic Special movepool in NU standards like Focus Blast, Signal Beam, Power Gem, Thunder, Thunderbolt etc. it has a good niche (in my opinion) in my NU team.