Schwalbe Marathon Plus. At least the puncture resistance. Slow, heavy, slippery, can be hard to get on wheels but pretty good against sharp things
I've had Marathon Plus for nearly 15 years because recommended by dealer and the cross section of the protection was like 5 mm thick. I didn't know better then, I also didn't do much effort to find better.
I think over that period I had a couple dozens flats (about 2 / year) due to punctured, also in the center despite the thick blue filling. But I could live with that.
Though I ceased to use it, I think it was 2015 or 2016, after like 3 punctures in 2 months, at that time there was a new version of the Marathon Plus that in my (Dutch language based) region was named "onplatbaar".
When trying to find an explanation for those sudden and quick flat occurrences, I noticed that the rubber felt like softer than before.
All 3 punctures were caused by an object sticking in the rubber and craving its way through the blue. One occasion it was like a round stone, it even hadn't that sharp edges.
I decided to do a test. I kept (and keep) a set of complete spare wheels, all of them but 1 had still the older version of the Marathon Plus mounted. I replaced the rear wheel by one of those. I had 4 months no punctures. I put the new model wheel back, it took 3 weeks to a next puncture, and again a little stone, that punctured the tires surface rubber and got "catched" by the protection layer to not escape anymore.