#1st choice: Webro WF100
#2nd choice: Webro WF100
#3rd choice: Webro WF100
# reserve choice: Webro WF100
There's the cheap crap and there's the right cable.
The difference in price isn't significant. At trade rates the difference in cost between the good stuff (WF100) and the worst (RG6 / "
low loss" coax) is roughly 15p per metre. So on a typical roof-to-lounge drop the saving is under £2; a difference so small it's not even worth thinking about.
Any installer worth their salt knows what WF100 is, and they use it. I use some higher grade cable on occasion, but nothing lower spec than WF100 for aerial work.
Unfortunately the general public isn't so clued up on cable to realise it actually makes a difference. They think cable is cable and it's all the same. It's easy to see why. It all does the same job. The cheap stuff is more lossy though, and more prone to interference. It doesn't last so long either, so you'll be paying out for trouble-shooting/repairs/replacement far sooner.
Ask your installer what he uses. If it's not WF100 then......
You can tell Webro WF100 because it's written on the jacket every metre. It also has a distinctive look - solid copper core in a white foam jacket, then covered with a copper foil jacket and then a copper braid for shielding before the final outer PVC jacket. Cheaper cables use a steel or aluminum core anodised to look like copper, then covered in a silver plastic foil (Mylar) and aluminium braid shielding.