Most of the time I use Caecilia, which I think has always been the default font on kindles. I mean my first kindle the K1 had just that font.
I have used the condensed version at times on my basic and paperwhite, but now on my Voyage, the regular caecilia looks really nice. Its less squat and wide on it. Just about right.
I don't like it as much on my kindle app, but on my Fire there is now bookerly which looks nicer than the regular caecilia on the app. For some reason the app version looks different than the Voyage version. Might be in my head.
But pretty much caecilia it is. Even though the Palatino and Baskerville now look really nice on the Voyage, for my eyes I just don't find them as readable. My eyes keep getting "stuck" for lack of better word. They just glide smooth over caecilia. Easy. So I can concentrate on the actual story, rather than notice the font.