Depends on what type of pawn structure you want.
French Defence

I can tell you easily that 3.e5 is stronger than 3.exd5, but it also comes with more theory.
The strongest of all moves is 3.Nc3, but with it comes the most theory.

Depends on what type of pawn structure you want.
I guess I want to e5. Thanks comment.
I don't know what you think, but I think the French Defense is very useful but I don't know how to go for black and white. Do you think exd5 or e5 is a better variant?