Both are great knives. But I'd pick the endura 4.
The big similarity is that both are high-quality zytel-handled knives with metal liners, and both come in quality steels (though the Grip gives more choices). But when I look at the main parts, the endura 4 keeps winning for me. The endura 4's blade is more useful both for EDC and defensive use, than any of the Grip's blade options, at least for me. The Endura's opening hole works better than the Grip's studs, and the fact that a waved endura 4 is coming really blows this category away. And both have good handles, but the endura's is so much slimmer and makes the knife much more carryable than the thick Grip. The Grip's sole advantage is the axis lock, but the endura's lock is well-done and will hold up to what I ask of it, so the advantages on blade shape, opening mechanism, and carryability rule the day for me.
That said, I don't think anyone makes a mistake in buying a Grip, it's a great knife.
Joe