Data usage level is what? i.e. unlimited or capped.
Do you mind bundling telephone and broadband with one provider?
Given all the providers use the same VDSL2 hardware, there should be no difference in connection speed, the variation will be in
1) How quick they spot they can take orders from that cabinet
2) Performance at peak times, based on how much capacity they have in their network
3) Usage allowance, price, contracts etc