Which early game NPC is the better pack mule?

In general when I play RPGs I tend to be a bit of a kleptomaniac and a bit of a pack rat. So, of course Fallout 4's crafting system that leaves nothing to waste is enabling this behavior even further.

I have discovered that Dogmeat can carry a bunch of my junk, allowing me to range further and for longer, but is he the best choice? Can Codsworth or Preston carry more? I can find no number in the game enumerating their actual carry limit before it gets reached.

Basically Dogmeat is the best choice if you just want a pack mule, because he doesn't count for the Lone Wanderer perk. That means you can skill the perk and use Dogmeat, but still profit from the 50/100 additional carryweight which enables you to carry a lot more than you could with another follower.

Dogmeats own carryweight is 150 lbs, which is the same as codsworth and just a little bit less than npcs like preston garvey. Together with that perk on lvl 2, you can carry an additional 250 lbs. The only NPC which can outweigh that bonus is Strong, the super mutant, who can carry 270 lbs, but you lose the other advantages of the lone wanderer and only gain 20lbs more carryweight.