In terms of military strength it's either Iwagakure or Kumogakure, both having 4/5 stars. Konoha's and Kiri's military strength is at 3/5, whereas that of Susa has merely 2/5 stars.
As for population, Konoha is the clear favorite, having 5/5 stars in this category. Followed by Iwagakure with 4/5 and Kumogakure with 3/5. Suna and Kiri share the last place with a population of 2/2 stars.
In terms of economic strength it's clearly Kumo, having 5/5 stars, here. All the other villages have an economy of merely 2/5. So, all in all, Kumogakure appears to be the best/strongest village.
Those aren't assessments of mine. I got those infos from one of Masashi's newer handbooks, where all five great villages are rated in those three categories. Before the war that is, of course.