IMO, this is the most important thing: what you want to do with the bike.

If folded size or quickness of fold are not paramount, then assuming you don't have a huge budget -- I'm eliminating Moultons and something by R English -- Bike Fridays, high-end Dahons, and Airnimals seem like good bets.

Some old thoughts on getting a Bike Friday are below ...

The part-time epistemologist: If you're interested in a Bike Friday ...

Some new thoughts ...

Lately some new choices in ERTO 451 have been popping up such as Schwalbe Ultremos and a handful of quality ~34 mm wide tires crossing over from the BMX world. So if you're really confident that you want relatively skinny tires and getting high gears is an issue -- the slightly larger wheel will help you get above 100 gear inches with a 56-11 chainring-to-cog combination -- then it would be a good choice, IMO. Otherwise 406 gives you slightly lower gearing, with a bigger choice of tires and tubes, while being able to fit fenders with wide tires.

Assuming you're set on 451, based on anecdotes, I'd make sure that the bike is built with 57 mm long reach calipers to leave space for 32-34 mm wide tires. Over the years, the number of folks that have wanted to use wide tires for a tour or a gravel ride or a tire with some knobbies is a decent size. The weight penalty is minimal. And there is no replacement for displacement, IMO. Those extra few mm -- going from 28 to 34 for roughly a 100% increase in air volume -- makes a big difference in comfort and control on less than optimal surfaces. In short, it makes the bike far more useful.

As for a wheels, the high value performance wheelset is probably a handbuilt Velocity A23 wheelset. Relatively light. Supposedly rugged enough for a wide range of uses. Since this is a travel bike, you're probably better off with something rugged and a bit more mundane.