3G is going to give you the fastest connection rate as it is gradually rolled out. It's based on new technology, while EDGE is an extension of older technology, and often referred to as 2.5G. Which one you decide to go for, depends on the countries in which you intend to access it
Beware of the limitations of 3G. As I understand it there is only a fixed amount of bandwidth available per cell, and as demand goes up so the cell shrinks (and adjoining cells expand) to compensate. WHilst the numbers look inpressive, these are maximums in ideal circumstances, and if someone hogs the bandwidth in a cell in a rural area, it would be possible for others to lose reception.