Us buying some garbage players doesn't say anything about the strength of the Ligue 1. There have been several players who became good to great from that competition in the Premier League; Evra, Essien, Drogba, Koscielny, Sagna, Kante, etc.
Not too mention the quality of French footballers in general and the level of their national teams.
You could argue it's Premier League that is probably the most top heavy league from any League in Europe. Apart from the top 6 there is nothing.
Allegri is probably the only proven manager that is attainable from a rather small list. Because I get the feeling people want 'top level' managers who have won stuff recently when they talk about top level; Ancelotti, Conte, Klopp, Guardiola, Mourinho, Simeone, Allegri. I'd be very suprised if Arsenal manages to convince one of those guys to join.