Either will spell huge upset in France, i.m.o.. It is just a question of the timing. Macron is untried. He may be seen as 'safe', but, from experience of his term in power, he was full of promising ideas - which translated into nothing. An example: his big idea was to relax the employment laws so that shops could have more charge of their opening hours and open longer. I remember our local shops & supermarket getting quite excited - the end result was that some shops in some tourist areas (nearly all in Paris) were allowed more flexible hours. Great local disappointment.
If he is elected, I fear that France will have elected the hubris rather than the substance. What that could bring in a few years' time is anyone's guess. At the very least it will almost guarantee the election of a resurgent, bolder extremist party, I think, because he represents the very last throw of the moderate dice.
Le Pen - well, who knows? She may actually be the better bet for France right now. Certainly at the moment she is constrained and mostly reasonable and open to argument (I said 'mostly'). Perhaps she is what France needs - a huge kick and upset (not as extreme as I fear may erupt in the future) to shake things up and then she can be defeated in an election. I don't know.
Whichever, there are rapids ahead, no matter if the result appears to head for clear waters. Bonne chance a tous!