Mexico
I would put Mole paste on the list for Mexico because it is the kind of thing that feels useful once you are home, not just another airport purchase. The best version is usually the sealed jar, tin or packet from a normal supermarket, spice stall or food hall, not the most expensive tourist version. The reason it works is that it gives you a quick reminder of the trip without needing to keep a fragile ornament safe forever.
Mexico
This is exactly the sort of thing I like bringing back from Mexico: small enough to fit in a bag, but specific enough to remind you where you bought it. The best version is usually the sealed jar, tin or packet from a normal supermarket, spice stall or food hall, not the most expensive tourist version. It is also the kind of thing you can talk about when someone asks what you brought back, because there is usually a little story attached to where you found it.
Mexico
Hand-painted ceramic skull is worth adding because it feels like something you actually noticed while travelling through Mexico, rather than a generic souvenir. The trick is to choose the simple, well-made version. Small craft items look better on a shelf when they are not too shiny or mass-produced. The ideal version is modestly priced, not too bulky, and good enough that you would buy it again even without the holiday memory.
Mexico
Smoky agave spirit from Mexico, often sipped neat.