Not been with them long and have only really played a bit of BF4 whilst with them but Plusnet seem decent so far. I'm pretty lucky in that I'm in London and only about 800m from the exchange but I regularly get single digit pings on UK servers and seems pretty solid so far.
I believe they also do a £5p/m thing where you can get gaming traffic prioritised, along with some other bits but at the moment I can't see what difference that would make for me.
Never used Virgin myself but have heard enough horror stories to put me off. I've gamed with people on it, who on a say a Friday evening, just gave up trying to play because of traffic shaping, throttling etc. Though this is all second hand info.