I've no experience of Sky, but I migrated from Be Unlimited ADSL2+ LLU to PlusNet Fibre Unlimited 10 days ago. I was one of the unfortunate customers who got put on to the 40/10 instead of the 80/20 product. It seems this was a "programming error" in the automated sign-up process which ordered the wrong product from BTOR. Once the problem was recognised I was upgraded fairly quickly, and as far as I understand the issue has now been fixed with the sign-up process - perhaps a PlusNet rep would care to comment on that.
So although there was an unfortunate hiccup with my migration, I feel that PlusNet dealt with it reasonable well and I'm satisfied with the customer service aspect. As for the Fibre Unlimited product, now it's working properly I'm very happy indeed. Throughput has been excellent at all times of the day I've been using it, and other performance criteria such as ping times, latency, jitter seem very good. I don't use p-2-p, torrents or gaming so I can't comment on those, but downloads are fast and the service has been reliable so far - it's early days yet. But I'm certainly noticing that I no longer suffer from the dropped packet problems I had on Be.
My phone is due to be migrated from BT to PlusNet on Monday, so can't comment on that either.
Overall, I'm very happy I made the change to PlusNet, especially with the half-price rental offer for the first 6 months. Definitely a better deal than BT Infinity.
Dircon > Zen > Be Unlimited > PlusNet Unlimited Fibre