In Cebu Ayala and SM are definitely the two prime ones.
For some reason I have much more success in the nicer malls than the cheaper ones.
If I see a 7 or better and I have the chance to approach I am doing it.
There have been months where I have handed out as many as 200 numbers.
For one week try one thing, and the next week try another and use the one that got the most text backs in a week.