The best replacement for sprites is polygons.

The best alternatives to sprites are rated as following:
★★★★★  polygons
★★★★  3d models
★★★  fairies
★★★  icon fonts
★★  data uri
★★  base64
★  3d graphics
★  sticks
  elves

Your alternative for sprites is not listed? Suggest!
Speaking about sprites, one probably shouldn't forget about game maker.

Other search terms related to sprites and their ratings are:
★★★★★ game maker
scary monsters
You have in mind a companion for sprites and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of sprites in all years. Click on graph for more.
sprites
polygons
3d models