I was with Plusnet but ime there were outages, and the hardware they provide is not the greatest, though of course you could by your own router to improve that part of it.
As I am wfh probably 95% of the year, and it's critical I am able to do so, I went with Zen internet - effectively the First Direct of the fibre world.
Started off with a fairly fast connection, and a really high quality router - upgraded to full fibre about 2.5 years in, and then bumped up the speed to double the previous one for no extra cost.
The few times I have had to use support they have been excellent, the biggest and only outage (Aside of one day when there were a few blips) was a month or so ago.
Woke up on a Saturday to no internet and a flashing light on the router.
Diagnosed eventually as the router itself being the issue, and in the meantime I was able to create a dial up connection via a 25 year old mega long rj45 connection to at least keep working.
The new upgraded router arrived by Tuesday, and was happily pretty easy to configure and get everything back up and running, including the two routers I have set up as access points etc etc.