The best replacement for gulp is gulp alive.

The best alternatives to gulp are rated as following:
★★★★★  gulp alive
★★★★★  grunt
★★★★★  powerbait
★★★★  doa
★★★  brunch
★★★  broccoli
★★  live bait
★★  trigger x
★★  sip water
★  codekit
★  squidgies
★  fishbites
★  sip
★  zman
★  exude
  bait
  yeoman

Your alternative for gulp is not listed? Suggest!
Speaking about gulp, one probably shouldn't forget about browserify.

Other search terms related to gulp and their ratings are:
★★★★★ browserify
★★★★★ requirejs
★★★★ yeoman
★★★★ bower
★★★ livereload
bucktail
You have in mind a companion for gulp and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of gulp in all years. Click on graph for more.
gulp
gulp alive
grunt