Worth it or not depends on how much are you willing to spend on the coverage and speed of singtel mobile.
Wifi-calling and singtel wifi are both not applicable to starhub and m1. Singtel wifi has been free for the past years and they have been extending since it was first launched. There is no data cap for singtel wifi as of now and i'm unsure of the future. So far, it has been the same for the past years. I'm curious why lohsenglte mentioned on the 2GB singtel wifi data cap when in fact its still unlimited usage as of now.
Since you intend to sign up singtel fibre, you get another free account of singtel wifi for use on your tablet/pc. with this and your mobile, your media consumption is generally covered.
Oh ya, if you have CIS privilege with singtel, you can also join singtel circle. You get all the privileges, though u would not enjoy the bundled discount on subscription fee on top of your CIS discount, but your other lines do.. I used to have this arrangement until i decided to drop singtel tv and exit the circle.
bottom line, its not about the cost of the price plan but rather to me, its the pricing vs performance. I would have gone for M1 if they were to offer the same performance as singtel with a cheaper plan though, but in reality you give and take, like lonelyman said.