Have always tried to be with an ISP whom caters for a more premium user and was with PlusNet (untill BT bought them) then Easynet (until Sky bought them) then BT wooed me with FTTC.
Started out as getting 75Mb throughput and was syncing at nearly 80Mb however speed started to fall over the next year probably due to crosstalk to about a 70Mb sync.
Early this year i lost 10-15Mb over a few days and BT refused to accept there was a fault and refused to send anybody to fix it.
Decided to leave BT and after reading about AAISP as well as out mutual hatred for BT/Openreach i decided to switch.
All went well and the transfer was very smooth.
After switching they team at AAISP badgered BT with frequent line tests. Within a week i had an appointment with Openreach. Technician came out and found a joint box on my pole had lost its cover and was full of water. This and a few other bad joints were repaired and im back to nearly 70Mb sync/65Mb throuhgput so a great effort from the AAISP team in getting Openreach to find and fix my faults.

Its been a while since i was on a usage plan so i had no idea how much i actually downloaded. They only count downloads towards domestic usage and not uploads.
nearly one month in i think i will upgrade to their 200Gb/month tariff at £10pm extra as opposed to PAYG topups in 50Gb lots as it looks like ill regularly be over 100Gb.

Ignoring the issue from BT, i find the latency and page load times to be significantly faster from AAISP over BT. Ping times are generally 30-40ms vs 80+ with BT which makes VOIP more natural.

It is expensive but you really do get what you pay for.