I don't know if it's the best pasta available, but the most common here in San Pedro is Milano or Princesa (both about 24-29 pesos a package), and they do have whole wheat offerings. There is a selection of imported Italian pastas in the Jumbo and Iberia here as well, but I don't know how good they are. If you have some time to spare, I can get you their name and price on my next trip to them on Friday.
On a side note, there were a few Italian restaurants in Juan Dolio that were charging steep prices for their pasta dishes due to the fact they were using "authentic imported Italian pasta". They were using Milano and Princesa. Unknown if the Pasta Police were notified.