There is an online programme that compares all the European parties' position on the main issues. The EU Profiler will ask you a few questions about your political views then analyse your results and find the party that matches your results most closely. You can view results by country, as a list, a compass graph or a spiderweb graph. It's very well designed.
I was shocked to see how close the Francophone Belgian Socialists, Christian-Democrats and Liberals were from each others. They have almost identical views on everything ! They are all rated as pro-European (not surprising) and centre-left. Among Francophone Belgian parties only the Ecolo was clearly on the left and the Front National (extreme right) clearly on the right. It seems more diversified in Flanders.