The proper question you would like to ask, based on the Spanish question, is "Which countries would you most like to travel to?". It asks preference amongst all the countries one may desire to travel to.
The other replies to your question seem to miss the point of the question. Those questions ask something like "a cuales paises quieres viajar otra vez para ver mas?".
My question asks something like "a cuales paises deseas viajar mas que todos los otros"