I'm far better served by a headlamp than any of the many clip on book lights I've tried.
That said, many headlamps are too bright and/or have too much of a spot at book distance.
My favorite is the tiny Petzl e+Lite. Biggest downside is the 2032 coin cells, but they last a long, long time at the low power setting.
I also like the Zebralight H501, a single AA model, using a single NiMH LSD cell. Unfortunately, I find the low setting ever so slightly too low for reading, and medium is brighter than ideal. A different Zebralight model might be better, but this is the only one I've tried.
My wife uses and likes a PrincetonTec Quad, and seems to like it. But she's not as picky as I am. It's been a while since I've tried hers, and can't remember how it compares. But with four well spaced LEDs, it's bound to be floodier up close than many other headlamps.
Jack