If you need unicode (i.e. your app will take more langauges than english and spend a lot of time on that (hint! GUI hint!), the 3 is the way to go. Unicode supp

If you need unicode (i.e. your app will take more langauges than english and spend a lot of time on that (hint! GUI hint!), the 3 is the way to go. Unicode support is so much better... For the rest, it depends on the libraries you need...