BQM looks good should I stick with isp

BT BQM

This seems good to me but people may diagree, there are 4 people streaming and using internet from 4pm-9pm always.

Should I just stick with this BT fttc 50/10 if they can lower their price, rather than risk an ISP move?

Given the 4 to 9pm usage pattern then nothing wrong with the graph

If moving to another VDSL2 provider unless that one has a history of problems in your area, no reason to doubt it would be worse at all. Though remember others only do 38/2, 38/9.5 and 76/19 speed options, so to get the 50 again you'd need to be on the up to 76 Mbps service