What is the best surgery for imperforate anus?

Depends. It depends on the level of the defect. If the defect is "low" or close to the perineal skin, an anoplasty can be done shortly after birth. If the defect is high, then a staged operation is needed. Initially the child will need a colostomy (temporary). Second stage is creation of anus. Third stage is closure of colostomy after the anoplasty heals.
PENA procedure. Depends on the type of imperforate anus. A very low type can be corrected with simple anoplasty. High types will need a colostomy first then later repair. Most surgeons today will do a posterior sagital anorectoplasty. Recently laparoscopy has been shown to be helpful in certain types.