[aviditas]

If you like both of those artists, I'd suggest checking out Kimbra. She has heavy jazz influences and incorporates so much meaning into her music and videos. She does similar vocal layering to Imogen Heap and her live mixing of her own vocals is simply amazing.

[sk5t]

Oklou's album "Galore" might also appeal to an Imogen Heap fan, with interesting self-made layering of vocals, electronica, some cathartic moments, and the videos are pretty darn good too.

[bitwize]

Also recommend everything by Reggie Watts, a master of the vocal layering technique. His TED talk is one for the ages: https://www.youtube.com/watch?v=BdHK_r9RXTc