Essentially Orwell disliked the "pig" class of people, individuals who created truths to fit their own machinations. The pigs invented a reality that would seem to be for the best of all the animals and then changed that reality (the "Commandments") to support whatever behaviors would benefit the pigs. On a less intense note, I would suspect that he disliked the sheep who just mindlessly repeated whatever the pigs told them was true. Mollie, whose only interest was in herself and her sugar, also would come under fire. It's difficult to know how he would feel about the dogs. They were taken as pups and had very little chance to mould their own characters. And Moses probably would have come under the gun for his attempt to convince the other animals that "Sugarcandy Mountain" was worth the wait rather than trying to improve their own lot in life here and now.
I'm not sure that Orwell "liked" Boxer, but he seems to be the most noble animal in the story, even though his blind following of the pigs has some of the sheep and some of Moses in it.
This all suggest to me that Orwell liked people who told the truth and worked for the good of all and disliked those who used power (and language) for their own advancement.
I am sure Orwell must have had some likes and dislikes for the various characters in Animal Farm, but he does not make these feeling apparent in the book. In the book he is just describing the characters and events, without making value judgments such as good versus bad and right versus wrong. He leaves it to the readers to make their own value judgments.
Of course, the way book is written, it is not difficult for the readers to make the value judgments. I believe the primary reason for Orwell to convey his ideas through the medium of animals was to present the characters and events in a very simple way, unencumbered by the need to be realistic. This way he has managed to arouse and convey many feeling among readers without ever specifying his own preferences or values.
Some of the worst judgemental adjectives used by Orwell are like "stupid" and "foolish". But I believe these also are not meant to show dislike for the characters. For example, he has described Boxer as stupid, but this does not mean that he is showing disapproval for Boxer. It is just a simple way of describing his mental abilities.
Orwell valued honesty and truthfulness over everything else, and disliked the opposite. There is no question he disliked people who came to power and did not work for the benefit of the average person.