Quantum or b'twin?

Hello, I'm probably going to buy a bike, but I'm torn between two brands: b'twin from Decathlon, which is specialized in that area, and Quantum, a French manufacturer from the north of France...

I'm hesitant because, according to a friend, Quantum is a brand sold in supermarkets, and to me, supermarket = very low quality...

So if anyone has tried both types of brands, please share your thoughts, thanks :-)

( Quick question, are shock absorbers really essential on a mountain bike? )