There is no pokemon I actually dislike, and its very hard for me to pick favourites because there is just too many.
Also, if I like say Kingdra, it means I like the whole Horsea line. Members of an evolutionary chain are inseparable to me and represent one pokemon species. I can't think about Lairon without having Aron and Aggron in the back of my mind adding to the opinion.
So I tried picking one for each type (by primary types, and exclusively Normal/Flying for the Flying type, to give every pokemon an equal chance; in other words you are all doing it wrong, exploiting dual types to get more favourites on your list, ie Houndoom is Dark, pick an actual Fire poke too duh etc..), but by the end of writing this post, one of the favourites probably already changed, let alone in a few days.
Furret - Ive always liked Sentret and Furret, because they are so adorable compared to Kantos rodent and one of such that actually isn't pink.
Typhlosion - It looks friendly and cool at the same time, doesn't have a cliche Fire-pokemon coloration and I love how each stage is different even though they are all rather simple designs.
Milotic - It is a beautiful sea monster, which sounds like a contradiction. So elegant and mystic.
Luxray - Just when I thought Ampharos would be my favourite Electric Pokemon forever, they introduced the Shinx line, which for me as a big fan of felines was instant favourite. It has a great exotic color choice and ends up extremely cool.
Roserade - I did not care much about Roselia, because I just did not see much potential in it, but I was proven wrong when they fully expanded its line and did that very well. Every detail on Roserade is spot on.
Froslass - When I first saw the alternate female evolution of the hilariously cute Snorunt, I was at a loss of words. Its simply magnificent.
Flygon - It makes for a great antlion based pokemon and actually turns into a more dragonic than insectoid creature.
Lucario - This pokemon has everything, it is cool, powerful, has canine features and an egyptian vibe, and was the first Fighting pokemon to take the special side of its type to a serious level.
Drapion - What a creative take on a scorpion, with the symmetries and alternating purples, as nasty and creepy as the real thing.
Staraptor - Its simply the coolest of its bird bros with that stylish haircut and the grey shades.
Gardevoir - a green haired humanoid Psychic pokemon? I jumped in excitement when I first saw a picture of Ralts. Its one of those good-hearted pokemon in their world full of threatening faces. Not to mention it also got an offensive addition with Gallade, which caught me totally off guard and is an interesting shift.
Weavile - It is a cold vicious predator, and it absolutely looks like it.
Galvantula - A furry electric spider? Fascinating! Yellow and blue/purple contrasting shades? I'm sold!!
Cradily - It looks the most ancient of all the fossils we have seen so far, very exotic and peculiar.
Banette - Freaky and not here to play anymore. Just wish gamefreak would remember it and give it an evolution too.
Salamence - Sleek and menacing. I love its evolution, mimicking insect metamorphosis was ingenious, there should be more of that in non Bug territory.
Steelix - A huge but cautious boulder worm turns into a scary monstrous steel serpent. After 5 generations such a core elemental change is still rare.