Soldato
I didn't think the story line in the first game was that great. Found it boring. Also the game play was frustrating.
I'll still play the second though for the shiny graphics.
Did you read all the little bits of lore? I usually don't bother in these kind of games as it's generally quite generic, but I found it pretty intriguing in HZD, and when I started piecing everything together I was hooked, looking for every little bit of info. It's definitely up there in my top 5!
Also really enjoyed the gameplay, so much that I replayed it straight away on NG+ (although partially to 100% the achievements as well - the only game on Steam I've done so)