I’ve used Safestyle once (windows at front of house), St Helen’s Glass once (for the conservatory) and Coral twice (once for windows for remainder of house, once to quote for a PVCu door) since we moved here (Baildon) in 1998.
TBH the product is as good from all three as each other; the salesman for Safestyle saw us coming, price was ok but the finance deal was silly.
Coral were fine both times.
St Helens were great for the conservatory but different salesman for the door was dreadful.
However, compared to the salesman from Northern Trade Windows of Pudsey, he was fantastic. The NTW salesman ticked all the boxes on the “bad double glazing salesman” ticksheet and then turned it over & ticked them again from the other side
We ended up simply repainting the existing hardwood door, which I had fitted myself the year we moved in. Two coats of undercoat & two of white glass are a LOT cheaper than a PVCu door