M1 - Probably currently have the least market share in the mobile market
thus their cust svc is excellent. They do throw in a lot of freebies to attract and draw cust. When they first started out, cust svc is negative, nv pay bill for 2 mth threaten to cut ur line already. But now they are humbled.
So folks no harm signing M1 cos they now have chng and have excellent cust svc.
Singtel - Supposedly to have the biggest share of the mobile market. Cust svc is negative cos they think they own the whole market now. So perks and benefits wise, they dun really give out a lot.
But still, they are the largest telco in sg for a reason, so no harm signing them up as they provide fair svc to all consumers.
Starhub - Probably a strong competitor in the market. After losing the barclay's rights to Singtel, in some sense, they do try their best to retain and attract cust. Cos they want to win back the market. Have excellent cust svc cos their motto is to provide a special cust exp. Sometimes u do have to be firm with them in order to get the perks and benefits.
As long as u feel u're right, and u insists in it, Sh will give in to ur demands, but not always. And this area as compared to Singtel, they proved themselves to be stronger as no matter how u insists, Singtel will not ggive in to u.
Just my 2 cts worth