What's the best computers to run programs like R and ArcGIS?

I'm looking at getting a new computer and I'm pretty heavily leaning towards getting a Mac, just for the convenience of compatibility between the Mac and my iPhone mainly, and it's also pretty good for someone like myself who is a student. But I'm also going to be needing to run programs like R and ArcGIS on it and was wondering if a Mac was good enough for this or should I go for a PC? And if so, any suggestions on which particular laptop?

None of us know what R and ArcGIS are, so give us the URLs where you found them.