I have a rather large library of mostly sci-fi and fantasy. Right now there really are a large number of great series.
Number one for me is George Martin's Song of ice and fire series. The 4th book A Feast for Crows should be out Nov. 8th, it been nearly 4 years since A Storm of Swords!
Next is Matthew Woodring Stover's Caine books: Heroes Die and Blade of Tyshall. They are just extraordinary both in story and the explicit violence that no other series I've read has approached. I saw on some site that he's going to write 2 more, but haven't seen any more news yet.
Steven Erikson's A Tale of the Malazan Book of the Fallen series
book1 Gardens on the Moon book2 Deadhouse Gates recently came out.
Micheal Stackpole's Dragon Crown War cycle
Dark glory war, Fortress Draconis, When Dragons Rage, and The Grand Crusade
In sci-fi
W. Micheal Gear's Forbidden Borders Trilogy
Requiem for the Conqueror, Relic of Empire and Counter Measures
Its been out for years, but still good
Peter Hamilton's Night's Dawn Trilogy
The Reality Disfunction, The Neutronium Alchemist, and the Naked God
This series has also been around, when they came out in pb there is a part 1 and 2 to each book
and Pandora's Star which has just come out in pb
Basically anything by Timothy Zahn - The Icurus Hunt to name one
Harry Turtledove's excellent alternate history series where the south won the civil war is now in its 8th book Drive to the East, where the CSA has the USA on the ropes as WW2 rages truly around the globe.
Really are too many to list