What is the most successful antibiotic for a sinus infection?

Depends: There is no one antibiotic that is the best. It all depends on each situation. But i can tell you that zpack is particularly not good for a sinus infection (its better for lower respiratory infections). Unfortunately everyone loves taking in because you only have to take it for 5 days.

Sinusitis Antibiotic: There is no "best" antibiotic. Nearly all antibiotics have the same effectiveness in treatment of sinus infections. Most guidelines recommend Amoxicillin as the first choice. Sulfa/tmp or Clarithromycin for pencillin-allergic individuals. The most active antibiotics are Moxifloxacin and levofloxacin, and are used when another antibiotic has been used within six weeks or for antibiotic failures.