Gita

Which is a real constraint dressed up as a trivial one. Most second pairs are packed for exactly this.

One criterion: does it give you blisters on a long day. Everything else is negotiable and that is not.

Which means the shoe has to be broken in and tested on a genuinely long walk before the trip, not around a shop. Two full days at home tells you more than any review.

Socks are half the answer and get almost no attention. A good wool sock in a mediocre shoe beats a cotton sock in an excellent one, every time.