Hmmmm... This is a hard one, but I'll answers anyways, despite problaby changing my mind in a few years
Well... Capitalism, I would say. It has its disadvantages, though.
Perhaps capitalism with the Keynesian alternative?
Slovenia, Estonia, Latvia, Lithuania, Poland, the Czech Republic, Slovak Republic, Hungary, Romania and Bulgaria (honestly dont know if they are all in EU..)
Please tell me how Poland, Hungary etc. are soclialist...