Best physics by far. Everything has real weight to it, and the NPC's generally have more realistic reactions to everything, as they all have hitboxes for individual limbs and react accordingly. It makes all the chaos that much better. It has a really good and focused story too. That said, it's not the best one. They stripped down a lot of features from the previous games, and it's pretty bare bones in terms of gameplay options. Lots of driving, lots of shooting, and that's about it. The graphics are fine, but showing their age too. The environments have a very washed out and muddy look to them. At least in the vanilla version. If you're on PC, mods can fix that problem.
GTA V is probably the best one overall. It brought back all the gadgets and whatnot, and it's a more complete experience.