I think II was by far my favorite, simply because it was the one that I felt best integrated the different character types into the game. There are unique things for each of the three character types to do (although, admittedly, the Fighter still gets short-changed in the sidequest department, but at least there's one set of Fighter-unique events, which is one more than any other game), unique solutions for most of the puzzles depending on which class you are (most notably, most of the elementals as well as the final sequence), and a timer that generally doesn't restrict your activities while keeping the plot on target. It's the most fun to mix abilities in, as well - did you know that even as a Fighter, you can cast spells in combat if you DROP SHIELD before being attacked, then GET SHIELD when you're done? Most of the other games restricted the class-specific sidequests to collecting spells, breaking into a few houses (and III didn't even do that much for the Thief), and a Paladin quest or two in the last few games. III advanced the series' technology a fair bit, but removed most of the fun in the bargain - I agree with the list of good parts, but I argue that those are almost the only good parts. IV tore down most of the walls between classes, since Fighters and Paladins got Climbing and the buggy interface forced the Paladin to gain Magic as well, which results in collecting some spells you can't really avoid (and definitely want to, in at least one case). I hope I don't need to go into V's flaws, although the things it managed to do well were a treat.