I'm planning a rtw trip, leaving in january. basically i have to decide on visiting either north or south america for probably about 3-4weeks. It will be the first destination on the tour. which place will i have the most memorable travelling experience in. any opinions welcome. thanks!
As you have only 3-4 weeks and you will be there around January, I would say you either visit Chile/Argentina or some country (costa rica for example) in central america.
North America can be bitterly cold in January, some Andes countries (like Peru and Bolivia) have rainy season.
But 1 country, maybe with a side trip to a neighbour is more than enough for 3-4 weeks. That way, you will avoid you will be tired of travelling after one months already.
How can you compare the two? Or by North America are you refering primarily to Mexico and the Central American countries? But if you are talking mainly about US and Canada compared to South America, well, you really can't compare since they are very different cultures - North is a western culture very similar to your own, and South is Spanish speaking and mainly developing nations . It really is a matter of which one appeals to you.