The list of just my favorite authors is too long to post here, but I'll hit a few of em. I'm a big fan recently of urban fantasy, but have always been a fan of scifi/fantasy books. I'll try to list some that have not been posted a ton already.
Love both series by Jim Butcher were great although the Dresden books are in my top 10 of favorites for sure.
I really enjoyed the Recluce and Corean chronicles books by L.E. Modesset (both are great but recluce is longer).
The Ender Books and Alvin books by Orson Scott Card are great.
Most of the series by David Eddings
The first bunch of books by Laurrel K Hamilton (till she decided to just write soft porn).
Many of the GREAT books by Steven King (nothing great lately but he used to be awesome.
In a similar way to Steven King, the early books of Piers Anthony were great (Bio of a space tyrant, Early Xanth, Phase Doubt etc).
I enjoyed most of the work by Robert Aspring *gleep!*, his new dragons luck etc series is good as well.
Racheal caine's weather warden series is worth reading.
Many of the series by Jack L Chalker should not be missed. HE's twisted...but usually in a good way. He has a bunch of good series to read. Start with River of the dancing gods or maybe the Well World books...but there are a bunch of good ones.
Robert Heinlien was a GREAT author for his time. Might be harder for newer readers to get into him now adays (there were very few good sci-fi authors back then)..I loved him in my early teens.
Don't be put off by the second and third book in the dune series by Frank Herbert (I was the first time). It's a great series and worth reading (more then once for me). It picks up again after the third book big time.
Timothy Zhans Star Wars series was great. Best continuation of the original movies I have seen. Really enjoyed them.
Many of R.A. Salvators books and series were great, and he even melds them together a bit sometimes. Drizzt and Pikel are great characters...though his latest books have been kinda depressing.
Terry Pratchets books are hit or miss, but some are histerical...some are just good and a few I got really bored with. Over all worth reading though I'd say.
The Earth's Children books by Jean M Auel (Clan of the cave bear is the first) it quite good and worth reading.
Much like David Eddings books, the Riftwar Saga by Raymond E Feist (and some of his other books) are quite good as well.
A brief mention of Mercedys Lackey should be made...not a huge fan of all the books, but many of the series were quite good.
Similar to Mercedys Lackey ....Anne Mccafrey (I'm destroying alot of these names) is a great writer with quite a few good series.
Margret Weist and Tracy Hickman have written many good books....including their great Dragonlance books. Many other good series were written by them as well (death gate books etc).
Also fan of many of the series by Patricia Brigs (mercy Thompson series and spinnoffs etc). Love urban fantasy
Kim Harrison is also a great author but I may have missed a book or two of hers since I haven't seen anything from her lately.
Ok...I'll stop there or i'll go on all night. There are tons of great books and authors and I certainly can't pick just one.