Personally, I'd avoid Plusnet.
I've been with them since 2012 but I'm now about to leave. Customer service has dropped considerably in that time and prices are expensive once your deal expires and they won't match new customer deals.
eg. In 2012 I was paying £18.99 for Line Rental, Unlimited Broadband and Anytime Phone Calls.
Since my contract expired, it's become ever more expensive - I was shocked to find out how much I was actually paying recently - they break it down into separate payments that make it harder to monitor eg. Line Rental is best paid using their Line Rental Saver as a lump sum every 12 months. You then pay separately for your Broadband Package and your Phone Package which are usually 18 months so they don't renew at the same time. The fact the line rental is separated can mask the true cost.
I thought mine had risen to around £26 per month but discovered it was actually now £33.45 (!) and that's with a £2.50 discount because I threatened to leave. So it would be @ £36 pm without the discount. This is for 6mb broadband not fibre (delivered speed to my house about 2 miles from the exchange and only a few hundred yards from the nearest cabinet).
Also, if you router has issues, mine did, after 12 months, they won't replace it for you. You're told it's out of warranty and you'll have to buy one so you can be left paying for a service you can't use because the provided router has failed.
Another issue is reliability. My neighbour, who originally introduced me to Plusnet in 2012, quit 2 years ago now because of stability issues. I have regular short sync drops although my reliability is quite good.
Would I recommend Plusnet now? No. Expensive packages once your initial deal expires, yearly price rises, customer services who won't replace equipment, reliability issues...
BTW, it's not the same as BT, my neighbour is now on BT and has much better reliability. I can't afford BT so I'm considering Vodaphone fibre now @ £28 per month for the same package as above but with a guaranteed 19mb to my premises and £7 per month cheaper than Plusnet.