That's very true. I've been with Virgin for years and have no trouble - never lost the tv signal and broadband downtimes have been very few and for short periods.
All depends on whether you live in a cable enabled area provided by Virgin; a high speed internet from BT or you are relying on the old telephone lines.
I've been with Plusnet for many years, largely because they have a free to call UK helpdesk, and they're relatively inexpensive for their 'unlimited' tariff.
As with any other non-cable ISP, they use the same wires between exchange and house, and their performance and reliability is mainly governed by how good or bad Openreach is in your area.