I saw three on a recent visit, and the best one was in Viscri. Although the road to the town is now paved, it is still a bit of a pain to get there. Once there, especially during the low season, one has to look for the old lady who keeps the keys to the church. Inside is fantastic: a modest church, a neat fortress layout, and a creaky tower/lookout. The hunt for the old lady was the best part as we were able to interact with locals, and she also showed a few things here and there we would have missed.

It is true that the area is littered with fortified churches. The ones listed bu UNESCO are fine, but I suggest really hiring a car and going out to explore. Copsa Mare, for example, is only 2km from Biertan, and has a creaky old church in a nice compact little town right in a middle of a small valley.