I would have to say halo series.
i have halo,halo 2,halo 3,gow and gow2.
gow is fun but it just cant beat the classic halo combat evolved and the amazing online gameplay of halo 2 and halo 3.
the reasons:
1. halo is classic
2. in halo 3 you can forge your own maps, go into theater after every game, record video clips, put screenshots and film clips AND forged maps into a fileshare for other people to download.
3. halo 3 has more options to enhance the gameplay like you can boost the speed decrease the gravity not only that but up to 16 players in 1 game.
4. halo 3 has much more glitches and easter eggs
5. halo 2 and halo 1s campaign r amazing
and i can keep goin on. still gow1 and 2 are great games but halo series r bettr and yes halo has halo wars anothr epic game.