For me this is definitely a “depends on what I’m in the mood for”

I think a lot of bechamels are a little too plain to carry the dish.
I would say the most consistently good of those would be Alfredo, at least out of the ones I’ve had even the lower quality ones are decent. I’ve had some very bland carbonara for example.

Cacio e Pepe is the most underrated here. Simple but great!

I think for my personal taste it’s between carbonara and amatriciana.

I don’t know if you’d consider it a sauce for the sake of this poll but aglio e olio is also fantastic!