Experience
I've personally owned two fully functional Apple computers, and I don't think either one qualifies as "best". They were good, but not that good, and each one was uniquely annoying, yet kind of interesting in its own way.
"Best" Apple computer: Core2Duo MacBook BlackNotPro - Core2Duo meant decent performance and Windows 8 ran like a breeze on it, but the thing got uncomfortably warm when it was working hard (so much that if I was sitting down, I had to shift the whole computer over to my right leg so that my left leg could cool off), the keyboard's key collection was "sparse" to say the least, and the trackpad was lacking a right click button. I traded up to a ThinkPad tablet and never looked back.
Worst Apple computer: PowerMac G5 - Coolest looking computer I've ever owned, unfortunately, it was all looks with nothing to show for it. Performance was subpar at best, software selection on PowerPC architecture is piss poor, connectivity was downright mediocre (3 USB ports, 1 display connection, no real microphone hookup), and OSX mouse acceleration was/is an unbearable hindrance to my productivity. This computer is currently for sale locally and has also been replaced by the ThinkPad tablet (twice the performance with almost a tenth of the power consumption, superior portability, and better connectivity to boot).