I realize that this is a thread necro, and I'm definitely late to the party. But this is an interesting topic, and it seems better to just thread necro than create a new thread on the same topic.
I think that there are two very different ways to look at the question of favorite paladin order. There's the which order's abilities/talents do you like best. And then there's the which order's background do you like best. Being more of a role player, I prefer the second question.
I'm rather old school when it comes to paladins. I personally don't like this semi-supporting leadership style of paladin. I prefer the old school "holy warrior" style of paladin. It seems a lot more fun to me. But sadly, that's not what's in PoE.
Furthermore, I don't particularly like the Darcozzi or Gold Pact Knight orders, because I don't see any central concept or ideology that defines them. The Gold Pact Knights seem more like a mercenary group than an order of paladins. And fighting for whomever pays you the most hardly seems like an ideology that should define a group of paladins. As for the Darcozzi, I can't even go that far. I have no idea at all what binds them together, other than being guardians and ambassadors of the Darcozzi family, which again hardly seems like something that should define a group of paladins. In both of these cases, they seem like groups of warriors, with the GPK's being more mercs while the Darcozzi being more guardsmen. But either way, not paladins, at least as I would see "paladins".
As for the Bleak Walkers, I can see them as paladins, almost certainly evil, though it's hard to see a binding ideology. Their description seems to describe more of means to their ideology than an ideology itself. But I have no idea what the ideology their brutal and merciless nature exists to support.
This leaves the Kind Wayfarers and the Shieldbearers. I can see these two as old school paladins of roughly similar flavor. Protectors of the innocent, etc., etc., etc.
Maybe what's really missing, at least for me, are ties to Eora's deities, since tying an order to a specific deity would pretty much define an order's philosophy. If an order was linked to Magran, a paladin would be a champion of the goddess of war and fire, and so forth, for example.
Anyways, looking at the paladin orders from an talent perspective, it seems to me that they're all relative weak and unappealing. The only talent that seems at all potent is Pallegina's Wrath of the Five Suns talent. It seems to me that other than the Faith and Conviction dispositions, the 5 playable orders are all rather generic in their abilities because their talents are so lame. Oh, sure, you've got to work your dispositions during your game play, and that's a good thing. But in terms of abilities, all paladins seem like they're pretty much the same in combat.
It would be nice if there was more differentiation between the orders in terms of what they bring to combat. It might also be nice if each order had specific requirements or strongly favored attributes that related to that order's special skills, talents, and/or abilities, so that paladins of different orders didn't have so much of a sameness about them.