I played them all too, and Gundam 1. Gundam, I thought, was shockingly bad and should never have been made, haven't given any thought to the sequel, don't even know if its out yet, but even if it is, I have no desire to play it. All the others, DW, SW and WO, all are Stellar games. Im playing through WO2 right now and its awesome. But I have to be honest, my favourites are the SW2 games, SW2 and SW2: Empires. I prefer the characters and the stories in SW to DW, and the games and all the extras are superb in the 2 SW games. My favourite of all is SW2: Empires. I love the Empires titles as the conquest map games are truly awesome to play. They're like playing Risk, except you get to take part in the battles and make certain management decisions to help your empire flourish. Very cool. The order I'd play them in is:
The reason I pick that order is not because its an order of preference, but because it splits the titles and the game types up nice and neat. Id never played a Warriors title before 360, and started with DW 5:Empires, and I loved both the battles themselves and the empires management part. If you're an old Warriors player, I expect you know what each one brings, if you're not, Id suggest starting with SW2: Empires because its better than DW 5: Empires, and the mix of the 2 gaming elements is great to get stuck in to on your first time.