I like Cebu Pacific for flying within the Philippines.
Their flights outside the country are usually at strange times. But at least they arrive in Manila and not out in Subic Bay...
My problem has been making a purchase with a Credit Card. Cebu Pacific just will not accept Visa and most Master Charge cards. They claim it is not their fault. HUMMM So try first to book online and if you are flying LIGHT (carry-on only) you can get an even better fare.
Check also the new Philippines Air Lines low budget fares. I do not know if they fly outside the country??
Good Luck!!