Having dealt with both I would rate pigs higher in personality than dogs. They are very smart, learn stuff quickly and definitely have individual personalities.
I always find it very hypocritical that the same people who have no problem eating pork are outraged over people eating dogs in Asia.
I think the key difference here is that dogs were bred for thousands of years, to be our companions, while pigs were bred as food. That's where it comes from.
You are looking at the extrinsic value of a pig, but when it comes to ethics, you should look at its intrinsic value.
A pig wants to live just like a dog does. They want to avoid pain and suffering just like a dog does. They seek comfort just like dogs. The fact that they were bred for a certain human purpose, doesn't change any of that.
Intrinsically, an ant, or a fly, wants to live just like pigs or dogs. It's ok to kill ants and flies because it is socially approved by the majority of humans around you. In some communities in china, it's ok to kill dogs for eating them, so a person would feel ok doing it. The animal doesn't matter at all, only the opinion of humans around you. As it happens, lighting dogs on fire is not widely accepted, and killing pigs for food is. It's the culture that matters.
In a society, people seem to taboo things which indicate a general lack of emotion toward other members of the society. With farm animals, there are social (and religious and legal!) rules around maintenance and slaughter, and farmers deal with large groups of animals, so the relationship between farmer and animal is one-to-many and doesn't leave much room for long term emotional bonds to form.
For working animals and pets, the bond is one-to-one, and involves working directly with the animal in question. The relationship with a working animal is much closer to the relationship with another human. Thus, killing a dog in a society where the role of a dog is to herd cattle makes you seem dangerous to the people around you, while killing a cow in a society where cows are food is explicitly sanctioned and not an indication that you might murder your co-workers.
Because when one curates something for a specific purpose, it is sub optimal to use it contrary that purpose. In this case, dogs have specifically been domesticated to be companions for humans for something like 15,000 years. Humans specifically selected for specific behaviors and traits for dogs for them to be more compatible with humans. In the United States, dogs are used almost exclusively as pets and helper animals.
Pigs have never been domesticated in that way in large numbers and have always generally been used as food, or for limited other purposes, occasionally as pets.
I think this difference in lineage and purpose leads to a very meaningful distinction.
You know how Hitchhiker's Guide to the Galaxy has a pig that has been genetically bred to want to be eaten? Like that is it's greatest desire in the world.
Dogs have been selectively bred over thousands of years to want to be our friends - to trust us, and to work together as companions. To deliberately kill and eat an animal like that is worse than eating any other.
You're conflating things at the species and individual level.
The dog species doesn't trust us (in any meaningful way). Individuals dogs do. Likewise, regardless of what we've bred "food" animals for, properly cared for farmed animal will hold the same implicit trust in a farmer as a dog does with his owner.
These evaluations need to be made at the individual level to make any sense.
As someone who has been around beef-cattle and also had milk cows growing up, cows are much the same way. They have a lot of personality and are not altogether different than dogs or anything else. Cattle raised for beef have a lot less human interaction and therefore have less "personality". Our cows knew their names and were very affectionate but they also had been interacted with since birth.
Most farm animals are probably psychotic and can't develop a personality just because of the circumstances they are raised in. If you threw 20 humans into a small pen where they have to live from birth to death they would probably be crippled psychologically and not appear very smart too.
Dogs have co-evolved with humans for tens of thousands of years, and demonstrate traits and behaviors that makes it much easier for humans to empathize and socialize with them. For example, you can tell when a dog is happy because their facial expressions resemble a human smile. Not so with livestock. Sure, you can figure it out after spending time with them, but it's inarguably not the same thing.
Yes, wrong example. Anyway, science has shown us that human-dog coevolution does have a noticeable impact on the way we interact with dogs. Specifically, sustained eye contact between a human and a familiar dog raises oxytocin levels to increase in both. The same type of relationship has not been demonstrated with other domesticated animals, to my knowledge.
As a kid in 4H I raised purebred Duroc and showed them at the Evergreen State Fair. You had to train them to respond to cane taps, move right and left, stop start, strike standard poses so the judges could rate breed characteristics, etc. I can assure you that a healthy, well-cared for pig has plenty of personality.
You'd be surprised how interesting a pig can be as a pet. They show amazing social behaviours, and they also seem to be quite good at understanding simple spoken communication.
« Some people have gone so far, especially with show pigs, as to slather sun screen onto their pigs when they know that they will be out in the sun for a considerable time and they don't want them to get dirty with mud. »
-- http://petcaretips.net/pigs-sunburn.html
You could also just keep your pet pig indoors all the time.