• I usually don't like zoom layers.
  • I usually don't like two portrait images side by side.
  • I usually don't like images with two or more of the same character.
  • I don't much like white backgrounds but they are alright. Black backgrounds are far better though. And transparent (if done properly) is even better as you can choose what color to use.
Post #112277 will probably always be my favorite background extension. I wish we had artists here willing to do more like that...

Anyway, here are some that might be worth extending:
pixiv #37304375
pixiv #30190567
pixiv #9223546
pixiv #29958842
pixiv #34756270
pixiv #14185995
pixiv #49618294
pixiv #44825313
pixiv #56048849
pixiv #15104475
pixiv #37807582
pixiv #43590201