I moved from Sky to Virgin last year, I’d have stuck with Sky but the new build we moved into are all pre-wired for Virgin and getting a dish up would have been a pain.
I can’t see any differences in picture quality on HD, and I’d even go as far to say that Virgin upscales SD a bit better than Sky Q did. No Sky Sports UHD on Virgin though.
In terms of pricing, they’re all more savvy on retentions than they used to be, they need to be convinced you’re actually leaving before the best offers roll in.