My #top100 #scifi Num:47 The Naked Sun

Amazon: http://amzn.to/2gZ5pEC

Social commentary masquerading as a Sci-Fi detective story. A planet of people avoiding human contact can only interact with each other via screens and their robots – uncanny and this was first published in 1956
Note: I realise now that the cover looks like a giant porn-star-bot having sex with a spaceship. I had this on my bookshelf for years as a child and it never occurred to me… 

My #top100 #scifi Num:48 The Robots of Dawn

Amazon: http://amzn.to/2gYlBGa

Spoiled by reliance on robots, lacking a spirit of adventure the human colonisation of the galaxy has ground to a halt. I tend to think the Fermi Paradox is all about apathy in the end, this book might have been the seed that planted the idea.
Asimov begins tying his worlds together here with the first mention of psychohistory…

My #top100 #scifi Num:49 Robots and Empire

Amazon: http://amzn.to/2fW12ch

Another Asimov classic. This one ties the Robots series and the Empire series together. One of my favourites. Daneel and Giskard wrestling with the laws of Robotics, basically the ethics of AI. 
Lots of philosophy, but not too heavy, and plenty of Space Opera to liven things up.