Say you're making a big purchase online and are given 2 shipping methods: Ems and Registered Airmail (the regular one). EMS is faster but it has much more chances of being retained by customs and charging taxes. RA is less likely to go through that, but it takes 1-2 weeks longer. What method do you go for? (Consider that, in this case, both cost the same amount of money).
Just a heads up. A recent order from the US took 7 days to get delivered to my house, in South America. With China's or Hong Kong's Postal Service, it takes about 3-4 weeks. Great difference.
I'm a regular eBay shopper. Actually, not just eBay. I buy a lot of things from shops overseas, especially those in Japan - and they always give you the option of either EMS or Registered Mail. Out of all the orders I've ever made, I've always gone with Registered Mail. The customs taxes that our corrupt EMS office charges us are just not fair. And they don't even bother to explain to you properly how the hell they managed to come up with that price for taxes. I'm completely fine with waiting a whole month or even more for my items - they even arrive in perfect condition, so no problem at all for me - as long as I can avoid unnecessary expenses.