What makes a country great? Definitely not size, that's for sure. I can take the example of myself and Malta: my parents are Czech but I was born in Malta and I've lived here for almost all my life. I love Malta because it has accepted me as one of its people, not asking anything in return, awarding me citizenship and taking care of me; I love the culture and language; I love the traditions of the people and the folklore, and I love the landmarks and places of interest. I am proud to be a Maltese citizen.
I agree with Dasa that it's largely a matter of opinion.
Many would use military might as a measure, others would use economic influence. A religious person might be more interested in the use of moral overtones in laws and public life, libertarians would be more interested in the extent to which freedoms and civil liberties are safeguarded, left-leaners would focus on social egalitarianism, and so on.