>>17216969From a technical standpoint, obviously whatever's out at the moment.
From a "made me satisfied and wowed constantly" perspective, Gen 4. D/P are underwhelming in retrospect, but everything afterward in that Generation seemed out to push the limits of the engine before moving on.
Gen 5 felt like a stopgap in comparison and wound up backtracking on the one major advance for the franchise it brought halfway through, and Gen 6 more or less followed D/P's "underbaked and conservative" route, except with nicer presentation and window dressing.