Probably not much help to the OP but having had the opportunity to fly both, for LCC travel out of Changi Jetstar are WAY better than Tiger if you have the choice..

In order of preference..

Pre - bookable seats (Buy online at their website and choose your seats on the spot.. including exit rows.!)

Leaves from the main terminal not the budget shed (sorry terminal)

20Kg allowance

And fares are just as good as Tiger. Particularly when they have their regular deals on. Flying Singapore - Cairns in January for S$88 each way. Even though it seems a helluva long way to go in A320...!