15/15/14 or 15/14/15

Doesn't really matter. 15/14/15 would be my pick if I had one.

I'm sorry, you're powering up Moltres to fight what now?

Edit: Nevermind, just realised you're probably talking about Regice and Registeel.

Beware because Regice can learn zap cannon. But it really does not make much of a difference.

It is super unlikely that one of them will hit a bulkpoint that the other does not. It's either 1 more hp or 1 more defense at level 40, so pick whichever you like. They will have the same CP too.

In theory I thought that 15A/14D/15HP could be marginally better than 15A/15D/14HP. This is since the defense breakpoints against the other pokemons fast attacks are usually passed by a good margin, implicating that the damage taken would be the same for a Mons with 15D and 14D, while the HP difference would remain.

The difference in damage taken with 15D vs 14D by the charged attack is of less importance as this attack is used much less frequently.

This difference is just theoretical, in practice there should be no real difference.. :)

I prefer 15at 15df 14hp

You do realise that Moltres is double weak to Golem right?

Edit: Why the downvote?

15/15/14. You'll be lucky if the extra Stamina in the other set provides any demonstrable effect at all. 1 HP, tops, and I doubt even that, though I don't have time to work the numbers right now.