My current read is Paul Preston's "The Spanish Holocaust: Inquisition and Extermination in Twentieth-Century Spain".
Judging by your comments after your read, I'm not sure whether this book takes a very different tack from the one that you read - it might just be you and me having different sympathies. Though I have to say, I'm reading this book with your comments in the back of my head and with a critical eye towards any pro-Republican bias - and while that bias is clearly there, so far I'm inclined to say the naked facts alone make it quite hard to side with Franco. But then I'm not very far yet (1933, still in the lead-up) and as I recall there are some leftist atrocities coming up still before the rebellion breaks out.