Zwei hands down. The storyline might not be as epic, but its more touching, as Lagi and Lundi bond. The game feels more cinematic with branching paths and some epic moments (like flying off the ravine for the first time) and boss battles. The dragon evolution system and bererk attack really add to the game. Graphically it's still beautiful today and the soundtrack is suitably epic. If it has any flaws, it's that it's too easy these days.
I love the original PD, but it feels very dated. The controls feel clunky and the game is very hard (I've never made it past Episode 6 without cheats because Episode 5 eats up all my credits). However, the intro is epic and the soundtrack killer (Episode 3's track still stands out with its bombastic drums).
Both are fantastic games. Any self-respecting Saturn owner should have both in their collection.
Zwei, definitely. PD1 is great as far as it goes, but Zwei offers so many improvements, first and foremost being the improved control and perspective;in PD1 it often feels like the game is forcing you to fly into an attack, while in Zwei it really feels like if you can't dodge an attack, it's purely your own fault.
Zwei is much smoother, both the models and the frame rate. There's more story, and what story there is is better paced. The multiple routes and dragon transformations genuinely add to the depth. I like the soundtrack better; it feels more enticing and fantastical and less arcadey. The bosses are more imposing, and more cinematic in their presentation. Last but not least, you've got a save function, a convenience I am very fond of. I feel like the limited continues in PD1 is an artificial way of extending the game's longevity rather than something which adds to the challenge in a meaningful way. Overall, I find Zwei both more polished and more memorable.
"It's not who does it first, it's who does it best!" - Mark Gruenwald