The best replacement for nerf bars is running boards.

The best alternatives to nerf bars are rated as following:
★★★★★  running boards
★  rock rails
★  sliders
★  step bars
  truck steps
  rock sliders
  running board
  chrome nerf bars

Your alternative for nerf bars is not listed? Suggest!
Speaking about nerf bars, one probably shouldn't forget about body lift.

Other search terms related to nerf bars and their ratings are:
★★★★★ body lift
You have in mind a companion for nerf bars and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of nerf bars in all years. Click on graph for more.
nerf bars
running boards
rock rails