I like Ringworld and most all the man kzin wars. Lots of stuff by Sheffeld like Resurgence.
I heard good things about Hyperion and read the first book which was disappointing and I will likely pass on the rest of the series
I have almost everything by Heinlen and Niven and reread them all the time.
Someone here mentioned Hogan last time and I like his stuff too
Two not so well known books I liked are interstellar patrol books by Christopher Anvil and I especially liked Threshold by Janet and Chris Morris. The second book of the series was not as good but the third book picked up again.