Is there grade/quality for spaghetti selection?
There is a legal difference: according to Italian law, pasta (which includes spaghetti) is made only with durum wheat. Other countries also accept soft wheat. The difference is in the amount of protein (mostly gluten): durum wheat has more, which in turn gives the pasta a somewhat snappier bite. Also, the cooked pasta stays eatable (as in, non-mushy) for a longer time.

Moreover, some Italian pastas are extruded through traditional bronze dies that leave a slightly rougher surface that makes for better sauce adhesion. 

Avoid by all means all stupid Italian pastas made for tourists. Avoid stupid novelty shapes and (most) colored pastas. Some good brands with global distribution that will not let you down: Barilla, Agnesi, Garofalo, De Cecco (thanks for the tip).