The best replacement for jmeter is soapui.

The best alternatives to jmeter are rated as following:
★★★★★  soapui
★★★★  grinder
★★★★  selenium
★★★★  loadrunner
★★  funkload
★★  gatling
★★  ab
★★  jprofiler
★  loadui
★  junit
★  siege
★  tsung
★  locust
★  opensta
★  hp loadrunner
  loadui web
  webload
  wapt
  httperf

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

Other search terms related to jmeter and their ratings are:
★★★★★ https
★★★★ junit
★★★ selenium scripts
★ badboy
You have in mind a companion for jmeter and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of jmeter in all years. Click on graph for more.
jmeter
soapui
grinder