Which is the best currency converter

I want to know which is the best currency converter would it be Coinmill.com or would it be XE.com or

I usually use http://www.oanda.com/currency/converter/, it can display graphs to display trends and you can make your own graphs.

All in all, if you know where you are going to exchange your money, it is probably best to keep an eye on their webpage as banks and postoffices, etc. typically set their own rates for buying and selling which can differ quite a lot from the office rates displayed at currency conversion sites, and sometimes even a commission applies.

The mechanics of a converter are not that complicated (just straight multiplying or deviding). The question is what bank gives the best exchange rate (and charges the less commission). And that is a well kept secret or at least the banks do their utmost to hide that from their customers. (Same as interest rates on savings accounts etc).
If you realy want to have a good exchange rate and pay a low commission than you need to do some research unless you know a site where somebody do that for you. (If somebody knows that pls let me know).
I just finished a trip to Japan and i always try to have as few Yen as possible when i am on the airport as the banks in my home country in Europe gives a very lousy rate. But to my supprice the exchange boot on Narita gave a better rate for Europe than that i had using an ATM just the day before. I could have made some money if i knew this before (:-)
Also keep in mind that paying with a credit card might be more expensive because the exchange rate is worth than an ATM (with your banking card)
Have a nice trip