If you will truely be playing with an equal level paladin at most times, and he goes Protection, at around level 30 go ice.
There is a special Blizzard build that works so exceptionally well with Paladins that it's relatively insane.
Protection Paladin does not melee damage for much, they stand there and do Damage to all the monsters attacking them with different types of thorns (Retribution Aura, Holy Shield, Shield Spike, Consecrate, ect) so he will be holding agro one 1 monster with the same TPS as a dozen.
Ridiculous -- After the Pally has rounded up his set, give him about 2 more seconds to lock Agro and just Blizzard -- you don't even have to Flamestrike if you don't want, all it takes is Blizzard.
Now if you're soloing, or PVPing, or he isn't going Protection then throw this build out -- its actually very weak if not in the right situation.