The complete package. Hardware and software designed by the same company = GOOD.
And in a word, I would say
performance. I always find it amusing when people resort to quoting system performance statistics when trying to justify why a PC machine is better than a Mac machine. Quote all the hardware specs you like, for me
performance is measured by the OS, the ease of use, the stability, the software, how productive I can be, and how much fun I can have using my machine - these are the factors that make me rank one machine superior to another - hardware is only one small piece. But that's just me.