which game takes more skills CSS or halo 3?

[Just some guy on this]

Im thinking of buying a game that would be a good challenge online, my friend had halo 3 and i played it for a bit and it was pretty good, but i never played CSS and from what i heard from my friend its pretty hard.
Which one should i get?

 

[Sweet Elf Balls]

Halo 3 gets really difficult online once you get your skill up. Some really good players,and a multitude of pretty good game types.
Some REALLY bad people too, like "lose the game because half of your team is horrible" bad. You get that a lot.

Still, great online. I'd recommend it over Css.

 

[Arnold the guv]

I recommend halo 3.