The short story is the place the genre developed and where many of the jewels are found. You should survey the landscape and see what you like. Canticle for Leibowitz and Flowers for Algernon are two of the most haunting novellas ever penned. Who Goes There is a classic of horror. Johnny Mnemonic introduces cyberpunk, and Snow Crash ended it.

Greg Egan, Robert Forwards are on the hard edge with universe driven plots. Robert Hamilton does space opera like nothing else.

Military SF is its own world, with Hammers Slammers maybe the best. Be warned: the author doesn't do gore but the horrors of modern, impersonal mechanized combat is conveyed as much as words can be.

The Terra Ignota series is fantastic.