What are the best Sci-fi and Fantasy novels currently out there?

That's a huge ask. For recent-ish fiction, I'd suggest
Ann Leckie's Ancillary trilogy (start with Ancillary Justice)
Robert Bennett Jackson's Divine cities trilogy (start with City of Stairs)
Katherine Addison's Goblin Emperor
Adrian Walker - End of the world running club

for older stuff ..
Roger Zelazny's Amber series (start with 9 princes in amber)
Roger Zelazny - This Immortal, Lord of Light, Doorways in the Sand (not a series, just some of his best)
John Varley's Titan trilogy (Titan, Wizard, Demon) & his Mars trilogy (start with Red Thunder)
Elizabeth Bear's Jenny Casey trilogy (start with Hammered)
Robert Jordan's Wheel of Time series (start with Eye of the World. tbh this kinda gets weak around the 8th book, but the first five at least are astonishingly good)
Frank Herbert - Whipping Star followed by the Dosadi Experiment
Jim Butcher's Calderon series (and for urban fantasy, the Harry Dresden books)
Garth Nix - Sabriel series
CHarles Stross - the Atrocity Archives & the rest of the Laundry series
Philip Jose Farmer's World of Tiers series (start with Maker of Universes)
John Scalzi's Old Mans War & sequels
John Brunner - Shockwave Rider
Mira Grant's Newsflesh trilogy
Louis McMaster Bujold's Sharing Knife series
James S A Corey's The Expanse series
Daniel Abrahams Dagger & Coin series (Dragons Path)