One thing about Clarence Thomas is that he has great respect for the Constitution and the oath he took to abide by it. He said that there have been quite a few times when his own personal opinions, values, and preferences disagreed with his interpretation of the Constitution and in these cases he had no choice but to abide by the Constitution. I can't ask for anymore than that from a judge.
The other 6 liberal justices, on the other hand, think that they know what is good for the country and I always get the feeling that their votes are based on their personal agendas rather than the interpretation of the Constitution.