Non genre-specific (free) advice: If those are intended for BookBub, cull like your life depended on it. 300 x 250 is pretty unforgiving when it comes to filling the ad with small text.
Also: What's the deal? I won't go so far as to say there has to be one (such as 99 cents), but what's the call to action? In Mary Portas parlance, what's the "point of difference"?
(If you like pina coladas AND getting caught in the rain, you MUST read this book!)
Another approach: Think movie posters. They go for a gripping central image and title, but beyond that there's at best room for one brief tag line. I don't know if people still walk past the theater and say, "Ooh, that looks good" like maybe in the olden days, but it's a damned effective medium, in my estimation.
Way old-school...
Superman: You will believe a man can fly.
Poltergeist: "They're here."
Blade Runner: Man has made its match... now it's his problem. (Editor's note: I had no idea Blade Runner *had* a tag line.)
See where I'm going with this?
Both of your images are strong but the text is trying to do way too much. Pare away.
(Good grief, who am I?)
