There are a lot of authors I feel who haven't gotten enough appreciation. Here's a pair I love that deserve more love.
Robin Wasserman: Skinned was the first of her novels that I read, and loved it. It creates a future world and presents a believable character that many can relate to. I just recently started reading her other series, Chasing Yesterday, and am in love with that as well, despite it being middle grade.
Maria V. Snyder: Though she's gained some more publicity over the last year, I've been in love with her books for the longest time. Her book Poison Study is one of the best books I've ever read. The kick off series is good as well. Check her out.