I like Steam's cause its not laggy like xfire, and Gcrusader you can download skins for xfire just to let you know. I don't prefer xfire though cause if your in those competition clans, they'll spam the chat room to you all day. Steam is better.
BTW Add me on xfire and steam, its Anthemjack for xfire, and look for =(e)=™Anthemjack on searching in the community.