Bought a DELL Inspiron 6400 back in 2006 with XP
I was advised to reformat twice a year to eliminate bugs and delete 'junk' at the same time.
Still running, under those conditions but now finding the 'left click' button is becoming unstable, so now using wireless mouse.
I've never used an Apple but admit they have excellent screen clarity compared to some windows machines I've seen.
Then I spose it comes down to just how the machine is specified by the purchaser too
I know with the Dell you could get various screens from the cheap and hard to see, up to the full HD whizzbang gear
I will 'look' at a Mac next time I upgrade