My vote swung between photo #1 and #4, and I decided to vote for...
"Bikini Tease"
Both are similar in the richness of tone, the great positioning of the models, and the beauty of the model themselves.
But while #1 is more mellow, natural, a bit on the calmer, darker side, #4 is almost supernaturally, and the look of the model is making it much more appealing, almost challenging. also the perspective, more than slightly from below, raises her to a higher ground, which adds to her challenge.