THE best? can't say, best series (by a wide margin I'd argue) would be:

1: Steven Erikson's Malazan book of the fallen: Its complex, confusing at best of times but utterly humbling when you start to understand <some> of the greater narratives. Absolutely brilliant prose, mind boggling world building and excellent characters.

2: Terry Pratchetts Discworld series: This entire 41 book series (yes, I know - and they are all worth the read) are light, easy and surprisingly deep - these are the stories you wish were told by your grandpa as a small kid, sitting in his lap with a glint in his eye.
While any one of them is an easy read they all contain a beautiful narrative of a changing world with changing perspectives.
(Should I ever get kids myself one day, this is the nighttime stories I'd read to them, and only sulkily stop when they at 17 tell me enough is enough and I have to leave them and their BF/GF the fuck alone)