Italian · La Marca
An Aperol spritz is three parts prosecco to two parts Aperol, so the prosecco is the largest single thing in the glass. La Marca is slightly off-dry with clear peach and citrus, which is why it suits the drink: it has enough fruit to answer Aperol's bitterness without going sugary.

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The one thing that matters
Do not use a bone-dry brut here. Aperol is bitter, and a very dry sparkling wine gives it nothing to lean on. Off-dry is the right call, and it is why La Marca ends up in so many of these.
It is one of the best value choices. La Marca is off-dry with peach and citrus, which gives Aperol's bitterness something to balance against. A bone-dry brut leaves the drink feeling hollow.
Traditionally yes. The Italian recipe is three parts prosecco, two parts Aperol, one part soda. You can use another sparkling wine, but prosecco's softer fruit is what makes the balance work.
About eight. A 750ml bottle is roughly 25 ounces, and each spritz takes three ounces of prosecco. One bottle of Aperol at two ounces a drink covers twelve, so buy prosecco slightly ahead of Aperol.