It is my favourite iteration so far. Whether it's the best though is a matter of opinion and can change from one person to another.
The previous games seem to have a lot more detail and effort put into them from what I've seen of them and they are rich with content and fun things to do, they sometimes will drive the play in different directions by the Sims wants and fears. This is something I feel the Sims 4 lacks. Saying this though none of the previous games were perfect, they all had their strong points and issues.
Even though I feel that the Sims 4 is my personal favourite I can also understand why it isn't as enjoyable as it's predecessors for some people.