1) Ubik — Though no Dick novel stands so far above the others that it can be labeled seminal, Ubik comes closest. The pinnacle of Dick's "What is Real?" era, Ubik contains the moments of reality-bending weirdness we expect in a tighter package. There are no lapses in plot, as can sometimes happen in a PKD novel. In this future, thanks to a cryogenic technique called "half-life," the dead can be preserved a little longer in a suspended dream state. This sets the stage for some very disquieting scenes.
2) A Scanner Darkly — Five to six books could rightly claim this spot; Do Androids Dream of Electric Sheep? or Time Out of Joint, to name two. Scanner, set in near-future Orange County, is a very mature work, containing some of Dick's most realized characters. Take the addled Jerry Fabin, for example, who sprays himself with Raid to exterminate imaginary aphids infesting his apartment. The banter between this oddball cast is memorable and hilarious. But Scanner is a tragi-comedy, as undercover narcotics agent Bob Actor becomes undone by his work. Biographer Lawrence Sutin writes, "Scanner was wrung from late '60s darkness, from Phil's times of hellish despair."
3) VALIS — Dick's most challenging work — but also his most human and literary. This is a largely autobiographical novel about his numinous visions of 1974. The main character is two personalities: science fiction author Phil Dick and Horselover Fat ("Philip" in Greek and "Dick" in German, respectively). This schizophrenic author searches for meaning behind his unsettling visions and crumbling life. VALIS, which stands for Vast Active Living Intelligence System, is poignant and funny, an exploration into mental illness, and one of the more unique novels ever written.