I could go on and on, but I only have so much time.
1). Twilight Princess had one of the best dungeon designs of the series, and not to mention
one of the best soundtracks.
2). The story, in my opinion, was remarkable. Unlike WW and OoT, which both released the backstory early in the game, TP's story progressed throughout the game, keeping it fresh and interesting.
3). The world was absolutely vast, with multiple areas to explore, it was able to keep me playing the game even after I beat it. The world under twilight was pretty cool too, shame it only lasted for the first 3 dungeons =(
4). Midna, Navi can f*** off