Ignoring VM for a mo, (virtually*) all providers will use Openreach and BT Wholesale to connect end customers to their own ISP infrastructure. How and where the ISP does that connection(s) will make a significant difference to how well it performs. More importantly is the ISP's own infrastructure - in laymans terms, some will just have the minimal amount and route out via a single transit provider, others may have full local CDNs from the big providers and route out via multiple transit providers and peering, or even own their own transit networks.
So, not all providers are the same!! Not even close. And these differences can make a whole world of difference, though for basic web browsing and email, most FTTC options will be more than adequate, no matter who provides the service. But if your needs are predominantly Netflix for example, then one that has Netflix caches at the ISP itself, or very close by, would be beneficial. If your needs a cock length bragging rights down the pub, go for one hosting a speedtest.net mirror. I would imagine Sky would work well if your primary need is NowTV.
Additionally, universally, without exception, the "free" ISP supplied router is utter shite in every respect. BT's HH6/SmartHub is the best of the lot, but still not as good as a reasonable router. BT customers take note, if you change your router for something different, you may lose access to BT Wifi when out and about.
*Some of the rural subsidised brandband schemes use non OR infrastructure, but this is rare, as OR won most of the contracts as everyone else knew is was unprofitable.