Build quality, that's all I care about.
My upper backlight tube just went out on my iMac8,1. That's after 4 years of "heavy" use daily (Adobe CS, MSOffice, FCPandX, Protools, VMware, VUE&C4D, etc.). The fix is to replace the entire screen assembly according to my mac support dude. I guess there is no way to know, but what I want is longer lasting parts for any new workhorse I buy, and I am not all that concerned about minute differences in speed. To use another bad metaphor, I just want the beast to plow on virtually forever, without dropping dead from exhaustion in the middle of next fall harvest, which Bessy just did. From a purely business standpoint, this horse paid for itself within the first year, so 3 years of return on that investment is pretty darn good I guess...ok, happy, but I retired from my consulting business this year and maybe I can get by now with just a laptop (my 4 year old MBP is still going strong, despite 3 logic boards under the first 2 years of Apple Care) and a thunderbolt. But, at the current crossroad, I am thinking to say the hell with media production and real work, and just live stress-free with a phablet and cheap windows boxes which can be had here in Asia for less than 400 bucks. In my SOHO that's quickly becoming a shrine to working class and a museum of old equipment: media converters, tape cameras, tripods, control surfaces, blabla, all I really need now is something to run PLEX, some large drives, and some wide screens hanging around the hut to watch the super bowl on. By now, I was hoping for translucent sheets of smart glass to do everything / anything I wanted to, but I guess I may have to wait until the next life to actually own some of those. A thinner faster iMac just does not excite as it once did.