I know it is more fashionable in the romance genre right now to be reading about billionaires in dire need of therapy, but my personal favorites have always been the historicals. Recently, I've discovered two series in particular that have really kept my Kindle clicking.
Elizabeth Hoyt's Maiden Lane Series 
Who would think that a romance series centered around the Home for Unfortunate Infants and Foundling Children in 1737 London would be so intriguing? I'm not sure if it's the Georgian setting (the wigs took some mental adjustments), the unique fairy tale framing devices, the fact that these books feature a mix of people actually accomplishing things rather than just aristocrats attending parties or the strong appeal of the individual characters that has me addicted. There are currently six titles in this series and I recommend starting at the beginning with Wicked Intentions .
Zoë Archer's Nemesis, Unlimited Novels 
I love a revenge story to a degree that should probably be alarming to my family and friends. This new series is set in Victorian London and focuses on a group of people who help seek justice for those who have been wronged and receive no help from law enforcement. Usually, they help the poor or powerless. The Nemesis members are a diverse and intriguing group, and the action and adventure have you turning the pages very quickly. There are only 2.5 books in this series so far, so it's no problem to start with the first one, Sweet Revenge .