Its become a regular occurance in America that historians and others rank the Presidents of the United States in order of greatness. In 1999 for instance C-Span published a list, the Wall Street Journal did another list in 2000 based on the opinions of political scientists and historians. Wikipedia (apologies, normally I don't cite them but here they do provide something probably quite accurate and worth using) provide a collection of these surveys going back over the last fifty years in the United States. There isn't such an institutionalised listing in the UK or elsewhere, that I am aware of, though we all no doubt have our lists of good and bad Prime Ministers- Peter Hennessy in the last chapter of his book on Prime Ministers attempts to list his league of the last fifty years.
The concept of listing is relatively strange. Go and see this exchange at Vino's Poltical Blog to see what I mean, Vino argues that FDR is his favourite US President, and the commenter Edmund argues that what Vino is really saying is not that FDR was great but that FDR was closer to Vino's political beliefs than any of the other Presidents, Vino agrees. Its interesting that the Wall Street Journal survey above explicitly said that it consulted liberal as well as conservative scholars because its editors beleived that the survey was intrinsically partisan- in the search for objectivity it was thought that a wide political sample needed to be taken (though as I will point out a fairly narrow one- where are the puritans or mercantalists?).
Personally I recognise that this is an interesting game- but have my doubts about how far its useful. Peter Hennessy's list of British Prime Ministers comes closest to a good list in my view- Hennessy doesn't seek to list them by ideological preference but by how successful they were at mastering the systems of government to enact what they wanted. Even there though, Prime Ministers have very different ideas of how government should function- some like Blair beleive in an unlimited executive, some like Attlee in traditional cabinet government- and that effects how they can manipulate the resources of government.
So we are forced back to Vino- can you judge a President on the basis that he didn't share your views? Of course you can- but the judgement will be contentious. There is a deeper problem though, in that you are setting a President or a Prime Minister a test he wasn't sitting for. How can you judge say Thomas Jefferson as a socialist, before Marx? How can you judge George Bush the younger as a socialist if he didn't want to ennact socialism? All you are saying as Edmund points out is that you disagree with them. Especially as you go back in time you run the risk of importing your own values to discuss the past with- so George Washington becomes a la Castro a soldier against imperialism, Thomas Jefferson a modern liberal and William Gladstone a progressive. The fact that Washington fought for the British in the 1750s and was liberating a Commonwealth on the basis that these people were white Englishmen who deserved the right of representation given to White Englishmen under the British constitution, that Jefferson was far more interested in the small citizen farmer on the classical model, that Gladstone's political thought had within it the incentives of avoiding hellfire and redemption- that his whole political career was a subset of his religious career, is avoided in a charge to force these men into modern categorisations. We seek to make them fit into our lists of liberal or conservative or socialist progress or regress- and so we lose their individuality as people.
There is always a tension in modern politics between our need to understand our opponents and our need to recognise that they are still our opponents. When it comes to history though- forcing people into parties that they don't particularly fit into and treating them as enemies or allies doesn't really help us learn anything. History is a resource to learn from- its far more interesting and rewarding in the long run not to make up lists but to actually work out why these very intelligent men and women thought the way that they did, why the world looked a particular way to them.
Lists tell us more about ourselves than they do about the past, and introspection has always rightly been accounted a frivolous occupation!