In one position I was given a MacBook PRO.  Prior to that I had no experience with Macs other than wincing at the price tag and moving on.  To be brutally honest I thought of them as posers machines, I was a snob.
The MacBook just worked.....beautifully.  It was a joy to use.  I got so much done but I can't pin down exactly why.
That said Outlook on a Mac is a leap back in time.  Features that Windows Outlook users have taken for granted for nearly 10 years are the Mac Outlook list of most requested features but with no sign of them being implemented.

Wireless repetitive strain mice are a must have.

Hardware assigned by rank is moronic.  Giving developers a 13" Windows lap top but an architect a MacBook Pro is an inverted pyramid of piffle.

The thing that makes the most difference to me is not the physical hardware (13" laptop aside).  The things that make the difference are

• Software set up




• Appropriate access privileges




• Ease of setting up and configuring local VMs




• Bureaucracy (preferably the lack of)




• Access to learning resources




• Team work




• Support from colleagues for the areas that are my weak point




• Sensible governance.  That is people who work towards solutions for the pain points introduced by governance rather than the other crowd who seem to think their job is to sit on their backsides and say NO