I have been with Plusnet for a few years now, with fibre broadband and home phone. My 18 month contract is coming to an end soon. I have found their customer service to be very good, and they gave us a good incentive to renew our last 18 month contract with them which sadly they won't do this year. They seem very up front, and accept that they may not be the cheapest deal, but their plus point seems to be their customer service.
Having been with AOL (aka Talk Talk) for many years previously the difference in customer service is very apparent. You could be lucky, get a cheap deal with someone, and not need to use their customer service, but if you do, bear in mind what
@T4tomo said, it's not an industry noted for its public service.
I haven't so far done the trawl of the comparison sites and "new customer" deals but from random inquiries it seems to me it's very much a lottery and it does seem with the proliferation of fibre broadband that prices are going up rather than down, so I might end up with Plusnet again just for the sake of a few pounds' difference and the hope that their customer service continues to be as good as it has been previously.