Check out the daily Political Notes.
(See also notes about airlines and air travel.)
The US makes international transfer passengers go through formalities comparable to immigration. Avoid routings with an international transfer in the US.
Avoid connections through London and Paris airports. Those airports harass passengers by making them go through security even in connections between domestic flights. In Paris this is so inconvenient and slow that I missed a flight as a result.
It is possible that these policies apply to all airports in France and/or England. Nice seems to have the same policy as Paris.
Vienna and Prague also make passengers go through security even in connections between domestic flights.
Vienna is bad for international transfers, too: I had to go through two security checks, one getting off the incoming flight and another at the gate. I think that is the standard practice in Vienna.
In Mexico City, terminal 2 makes passengers go through security in domestic connections. Terminal 1 does not. Alas, the main user of terminal 1 was Mexicana, which has gone bust.
Dubai airport requires a security check for international connections.
Hong Kong makes (international) transfer passengers go through security checks. So do Jakarta, Narita and Singapore.
Singapore is the worst, because security is right at the gate, so there is no way to buy drinks or fill a water bottle before getting on the flight. This also tends to result in a long security wait at the gate. Connecting to the Internet there requires giving the info in your passport.
If you consider an international transfer in Kuala Lumpur, make sure that you won't be forced to enter Malaysia, because they would take your fingerprints. And be careful because they might extradite you to be executed without giving you a hearing.
Frankfurt, Munich and Schiphol are convenient for domestic connections. For international connections, Frankfurt has taken to making people go through security, which is a pointless inconvenience.
Avoid international connections between different airlines in Bangkok airport. They require you to go through immigration to claim baggage and recheck it. If you need to get a visa to do this, it could cost you up to $100. That's assuming you don't get arrested for criticizing the king while in some other country.
If you know of any other airports with good policies, or with bad policies, please let me know (email rms at gnu dot org).
Copyright (c) 2009, 2011, 2012, 2013 Richard Stallman Verbatim copying and redistribution of this entire page are permitted provided this notice is preserved.