The best replacement for spybot is malwarebytes.

The best alternatives to spybot are rated as following:
★★★★★  malwarebytes
★★★★★  spyware doctor
★★★★★  ad aware
★★★★  windows defender
★★★★  avg
★★  avast
★★  superantispyware
★★  spyware blaster
★★  adware
★★  adaware
★  ccleaner
★  ad-aware
★  spyhunter
★  spy sweeper
★  spy hunter
  mbam
  spywareblaster
  defender
  adwcleaner
  spyware
  super anti spyware
  spydoctor
  lavasoft
  malware
  webroot
  spysweeper
  xoftspy
  spyware bot
  spy doctor
  spyware terminator

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

Other search terms related to spybot and their ratings are:
★★★★★ immunization
★★★★ tea timer
You have in mind a companion for spybot and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of spybot in all years. Click on graph for more.
spybot
malwarebytes
spyware doctor