The best replacement for ggplot2 is lattice.

The best alternatives to ggplot2 are rated as following:
★★★★★  lattice
★★★  matplotlib
★★  gnuplot

Your alternative for ggplot2 is not listed? Suggest!
Speaking about ggplot2, one probably shouldn't forget about error bars.

Other search terms related to ggplot2 and their ratings are:
★★★★★ error bars
You have in mind a companion for ggplot2 and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of ggplot2 in all years. Click on graph for more.
ggplot2
lattice
matplotlib