We were with Virgin for over a decade. The quality of the fibre service was very good. Probably had about 3-4 brief outages in that entire time. Left because I got fed up with the mid-contract price increases that the government specifically tried to outlaw and then they found a way around it again (it's not a change of contract if we say in the contract we're going to change the contract...).

So I rage quit and went with Sky Fibre a year ago, which is BT Fibre and is also very good. Sky were about the only BT Fibre provider when I looked that at least waited until the end of the contract before cranking the price up.

Downside with BT is they force you to use their massive white router, which shouldn't be necessary.

I don't think I've ever had particularly good customer service from either, but if you get something that is Virgin or BT Fibre to Premises then it should be good quality and hopefully you won't need customer service too much.