Both brands will serve you well.
You could also look into De Buyer Affinity, Demeyere Pro Line/Atlantis and Falk Copper core.
I have 4-5 years daily experience using Mauviel M’CookI own 12-15 M’Cook pans.
They are my daily drivers so to say.
I prefer my Falk & Mauviel 2.5 copper pans, but as daily drivers Mauviel M’Cook is hard to beat.
I would personally go for a thicker PLY pan or cast iron/carbon steel for high heat searing, that M’Cook, but M’Cook can most certainly still sear a great steak.
For quick sauteing and sauces, Mauviel M’Cook is hard to beat unless you compare it to 2.5 & 2.0 bimetal copper.
I would get a range of different type pans instead of just buying one brand pans.
They all have their strenghts and weaknesses.
