If possible, I'd recommend reading them in the order he wrote them. Seth Speaks, The Nature of Personal Reality, and on. Read them ALL over time, and then read them all again. You will never cease to find new insight every time you read them.
Also, "The Seth Material", while not an actual Seth written book, is an excellent "introduction" to Jane, the coming of Seth, etc.
30 years ago, Seth began lucidly introducing humanity to the concepts now being discussed in these forums: "attraction", "intention-manifestation", "subjective reality", etc.
His simple phrase "You create your own reality" encompasses these concepts entirely, and the massive scope of his books goes into explicit detail explaining how we create our personal reality, the nature of mass reality, the unknown reality, and everything in between.
The depth, breadth, cohesiveness, and elegance of his total body of work is unparalleled as far as I'm concerned.
Clearly I recommend Seth.
Ryan