BE all day long. BT ADSL are known for traffic shaping, throttling p2p, and having a 100GB download limit even though there are advertised as unlimited.
Also if you download too much data your DL speed will be capped for the whole month with BT!
Ive had both, and BE are way better, there support is also very very good on the forums.
Hasn't been the case for 18 months or so. They increased the trigger to 300gig then did away with it entirely and you no longer get a hard speed cap for a whole month if you exceed some random number.
P2P traffic is still shaped at peak times but thats it.