How far back were you planning to go? The original Shadowrun novel series consists of forty books published from 1990 to 2001. There was a brief revival with six books published in 2005 and 2006. The current run of novels started in 2014, with seventeen books and a handful of short fiction anthologies so far.
In the original series, the "Secrets of Power" trilogy by Robert N. Charrette are required reading because they launched the series and set the tone for Shadowrun fiction, and the "Dragonheart Saga" trilogy by Jak Koke gives important context to Dunkelzahn's death, which shaped the Shadowrun universe for the next decade. They weren't the best books, but they're okay. Night's Pawn and Burning Bright by Tom Dowd are both excellent and important. The best of the original series are Changeling by Chris Kubasik, Preying for Keeps by Mel Odom, Wolf and Raven by Michael Stackpole, and absolutely everything by Nigel Findley. You can skip Shadowboxer by Nicholas Pollotta and all five titles by Lisa Smedman. I thought Never Trust an Elf (Robert N. Charrette) and Worlds Without End (Caroline Spector) were awful, but they were unfortunately loaded with early Shadowrun lore — you may want to slog through them for that reason, but I can't recommend it.
The revival series includes the Kellan Colt trilogy by Stephen Kenson, which featured a bunch of characters from the "Shadowrun Duels" action figure series. All six books from the revival series were good, from what I remember.
The new series is also pretty solid. Russell Zimmerman's books have been my favorites. The only one I really didn't like was Shadow Dance by Aaron Rosenberg; you can skip that one IMO. I haven't read the most recent two yet.
