I would recommend HKBN if you have coverage at your area as its tariff is reasonable and the internet speed available is higher than the other providers. My folks are using it , and they a happy with the 25 mb internet
FYI, PCCW is a company with longer history in the market, however expensive and slow I would say (it is using ADSL).But at the end of the day, PCCW (Netvigator) has the most coverage so sometimes it is not depends on you to choose. Like my case, where I live only got PCCW as a ISP, the highest speed option for me is only 6mb and I pay even more than me folks. But me folks are using 25mb
If you look for very cheap tariff, i cable is your option. But u have to expected that u may end up with slow internet and crap service as thats what they a famous for.