Yeah Philip K. Dick is really good,
I used to have all 4 volumes of his short stories; I have never read any of his longer stories.
I liked the spanning of topics that he covered ->
- government and social control
- identity (psychology/ai): I loved second variety
- time and space (physics)
I remember thinking that his 2nd collected volume was my favorite
I believe you should check out Victor Borges's Labrinths (or fictions)