If the paint is pure black I would use CQUK. I have had it on my wife car for over 3 years.
If the paint is metallic I would look at CQ original. I had it on the same car for just over 2 years before I polished it off and went with CQUK when it came out. And honestly after the deacon the CQ was still going strong and didn’t need to come off.
I have used Gloss Coat and it is super easy to use. But it hasn’t been as nice as the CarPro stuff.
3 years with no polishing? It had to have traffic film and contamination on it after that long no? What about washing swirls? The car is black?