Tough question. I'm going to say the races that are discriminated because I can sympathise with them and there's evidence that they live in turmoil. The Khajiit only came to Skyrim because of the war and they can sell contraband items for a fortune, and all khajiiti are born skilled traders. They also have cute faces and voices which is a huge improvement over Oblivion, but they don't seem nearly as savage as they once used to look (ferocious even). The Argonians are cool too and I always do my bit to help one in need because they've some interesting gossip especially about Argonia, Black Marsh, where they live. Not as nice looking as Oblivion but they sound better and more civilised.
My favourite is the Dunmer though who I believe are either cockney or have a heavy Australian accent (I'm rubbish with accent recognition). They just sound so gorgeous and look like Hell, and you would too if you lived by an erupting volcano and had to retreat to Skyrim. They're an upstanding, hard working people that speak how they feel and would sooner spit in a Stormcloak's eye than they would salute him.