Ok so on the 13th of May Germans approached the Franco-Belgian border at Sedan.
Yes, the breakthrough was achieved on 14th of May.
You can claim that Poland fought better under harder conditions if you want, but you cannot claim they fought longer.
Hard to say which army fought better. In both cases high commands screwed up, low-ranking commanders and many units fought very well.
I would say Poland fought better than France and all of her allies in May (Fall Gelb). Because in May Germans didn't really have any great advantage over French forces (and their allies), and yet French, Belgian, Dutch and British forces were quickly defeated, but not as easily for the Germans as often presented.
But in June (Fall Rot) Franco-British-Polish forces were vastly outnumbered, just like Poland in 1939, and fought very well but stood really no chance against so overwhelming German superiority. Fall Rot was ended quickly but consisted of some very fierce and violent fightings on the Weygand Line.
Anyway - out of British, Belgian, Dutch and French forces in 1940, it was probably the French who performed best.
But the French also had the strongest army out of these four forces.
One thing which took place in Poland was not repeated on such scale in France - the Polish counteroffensive at the Bzura. The French nor the British never managed to organize a counterattack on that scale, as far as I know. Despite having much more resources to conduct counterattacks.
And although Bzura was in the end lost by the Poles, it was involving 1/3 of entire German army in Poland and most of their airforce for almost 2 weeks.
Another thing is that to crush Poland Germans needed to expend as much ammunition as to crush France.
But In Poland they were probably not taking care of how much ammunition they were expending, in France (after experiences from Poland - very large consumption of ammo, much bigger than all expectations) - they probably started to do so.
Both campaigns cost the Germans more ammo than American forces expended in the Rykyus Campaign (including Okinawa) which lasted for 3 months.
I have data on ammunition consumption in all these campaigns in number of tons as well as in number of rounds of each type.