Well, it might seem that I jumped in here, but, at least from my point of view, these are two cars, that are just two different worlds.
On the one hand you have the Bugatti. It is pursuing the old Bugatti values, first and foremost: perfection! The Bugatti's purpose is to be the most luxurious, elegant. However this time they added two more things: to be the fastest, and to preserve the ability to be driven as a everyday car.
I'm not quite sure about the 'most elegant' part, as I would take a Galibier any day, but in all other aspects they have suceeded.
The Aero on the other hand, well as I see it, it is an non presedanted effort to make the fastest car, but by apsloutly neglecting all other values that make the Bugatti the better car. I mean, in terms of comfort these two are as different as the British queen and M.Jackson (no dis-respect to the Brits!).
Let's see it like a David vs. Goliath fight.
Wich one's better? Well, that depends on the things that you like/want with hypercars.