I think where Macs can sometimes be challenged is in running games compiled to their OS. The 1st MAC my nephew got was a decently spec'd laptop and I remember opting for more RAM and better CPUs and GPUs. I was often suprised that MAC games I bought him didn't peform very well on it - especially since they weren't bleeding edge, recent releases. I put that down to just poor optimization by the dev team, but I think that's a legitimitate concern since consoles or Windows OS's are the primary dev platform for most games. That was 5 years ago though, and the MAC has gained some good market momentum since. I'm curious if the situation has since improved re. MAC game performance?
I'm speaking from limited experience, but yeah Civ V and anything Blizzard has made that I own run just as well on OSX than they do on Windows.
Of course for those games that don't run as well, there's always the option of just going and running Windows.