3.exd5 is definitely the way to go.  After 3.e5?! Black gets a good Advance French in which he can develop his light-squared bishop to f5 or (after Nf3 by White) to g4, before playing ...e6.  (Another way to look at it is that it will be like an Advance Caro-Kann, only Black will have got to play ...c7-c5 all in one move, while White is committed to a premature c3.
3.exd5 is far and away the main line - it has the advantage of bringing the Black queen into the middle.  although this cannot be exploited immediately as Nc3 is not possible, the queen does still become exposed in some lines.