It honestly depends on your team.
If you need an offensive Pokemon (Attack or Sp. Attack, Lucario can run both quite nicely) get Lucario.
Lucario also has a very nice moveset including Dark Pulse, Aura Sphere, ExtremeSpeed, Dragon Pulse, Bone Rush, Earthquake, Shadow Ball, Brick Break, Flash Cannon, Poison Jab, Blaze Kick, Hi-Jump Kick, Cross Chop, Drain Punch, Ice Punch, Water Pulse, etc., and decent stats as well.
Pokedex Entry and Movepool here