YSL is more original, more prominent, it was launched before Bleu de Chanel..
Bleu de Chanel is very unoriginal and borrows a lot from YSL L'homme
I don't say Bleu is bad. It's good. All Chanel's are good. However I don't need it at all. I have Allure, Allure Homme sport..But not this one...
Bleu is boring... Allure, Allure Edition blanche, even Allure homme sport - all have some character, they are recognizable. Not Bleu de Chanel. No wonder Polge made it without love

p.s. YSL L'homme is better than La Nuit and it's closer to Bleu.
Bleu is light. La Nuit is gourmand.