Despite the hype and popularity of other sio paos in Iloilo City, I still prefer Wewin's pork sio pao. It has a a gracious filling of pork adobo (flakes and sometimes even thumb sized pieces) and hardboiled egg. It's simplicity makes you appreciate the bun and filling combination more. And there's no need for sauce for this sio pao since the filling itself is "saucy". 
Besides they'll only give you banana catsup as sauce if you ask for it -lol.