Arsenal - Great to watch at times. Discipline is piss poor and they have a number of petulant little shits starting to creep in their side. But watching Henry is just brilliant and Van Persie's a cracking player too. And they're not winning all the time these days so it's hard to hate them the most.
Chelsea - My choice for most hated. Not only did they buy the title but their luck is unbelievable. They get given loads of free kicks and penalties and the number of deflected goals they get is unreal. People talk about Lampard's goal return as if it didn't come largely from dubious penalties. Throw into the mix the overrated Robben, Nigel "Carvalho" Planer playing centre half and that scumbag Essien and they're easy to hate.
Liverpool - I do hate them a bit, but it's mostly to do with their fans and the BBC constantly juicing over them. I think they have some excellent players and have become a very good team very quickly. Some good passing and it's all down to Rafa Benitez, who I think is the best manager in the League on his showing so far.
Man United - Large amount of residual hatred from the 90s - Ince, Keane, Hughes, Cantona - when they really did my nut, and we didn't have Blose to hate because they were down where they belong. Ferguson is a right bastard and a few of the players are arseholes. But Rooney and Neville (no, really) are world class. Good keeper, good full backs when Heinze's in, good defence as a unit when Ferdinand can be bothered. Weak in midfield. All in all less scummy than they used to be. When they play their one-touch game it's a great thing to watch.
So, in summary - Chelsea.