Can't Figure Out Which Baltic Country to Visit

Does anybody have experience traveling to Estonia, Latvia or Lithuania? I've settled on doing a Baltics trip next summer, but it's so hard to decide which country to prioritize of the three.

I have 12 days to work with, but I'd like to spend at least 6-7 days in one country to get a more fulfilling experience in one of them - and then maybe go to the neighboring country for a few days just to see something else. I'm fine with reserving whatever country I skip out on for another trip in a few years.

Any suggestions? I like going to small towns as much as big cities btw, so if one of them has better small cities/towns than the other that could be a factor.