My 
and research. I fly this route at least once a month.
Cebu Pacific
Minimum two-week advance purchase:
Round-trip, w/ travel insurance (169 NT), seat selection (140 NT per seat), no checked bags (very important when booking online) = 4,926 NT out the door.
Minus the “frills” as I like to call them = 4,487 NT
One week or less advance purchase:
R/T, no insurance, no seat selection, no bags = still a bargain at 8,096 NT.
Philippine Airlines
Minimum two-week advance:
12,274 NT just to get on the plane. Dunno what happened over there at PhilAir, but the days of 6-7,000 NT cheapies are gone.
Spirit of Manila
Anytime. $180-200 US (price in USD – as quoted on website). Unless you want to go to Clark, this isn’t worth it. That “one-hour” ride from Manila is a pipe dream. Take my word for it or not. Meanwhile, if you’re doing a last-minute, down n’ dirty, no-budget one-day visa run, you could hang out in Angeles and skip Manila altogether.
The pros and cons of Cebu Pac:
Pro: cheap.
Con: one flight a day which leaves at 1:25 a.m.
Pro: the outbound flight is never completely full.
Con: the return to TPE is at 10:30 p.m. – you arrive at 12:30 a.m.
Pro: getting in and out of both TPE and (NAIA) MNL is super easy at those hours.
Con: in both airports, this departure/arrival gate is always located as far from baggage claim, customs, etc., as physically possible.
Pro: NAIA Terminal 3 (currently only serving Air Asia and Cebu) is spanking new and has places to eat other than (or in addition to Jollibee’s).
Con: Taoyuan Terminal 1 departure lounge is still under renovation, meaning the perfume and duty free shops are open but there’s nothing to eat at that hour – this should change as they’re thisclose to wrapping up the re-mod.
Pro: CePac generally flies Airbus A320-200, so at most you’re dealing with 150 or so other passengers.
Con: the A320-200 has all the comforts of a city bus.
Tips:
If you want to buy drinks or snacks on the flight, make sure to have smaller bills on hand. They accept NT or peso. It’s like 80 NT for a beer. Drop a 1,000 NT note on the flight attendant and it knocks the whole system out of whack as they try to make change.
They aren’t fussy about bringing your own grub on the plane – just no booze.
280 NT for the seat selection is kind of a bargain/blessing if you travel a lot and know where you like to sit.
Try to be one of the last passengers on the plane. Self-evident.
Don’t bother getting fancy or detailed on the Customs Declaration form. Nine out of ten times there won’t be anyone at customs when you arrive at NAIA, or they’ll be out like a light in their seat.