The best replacement for quantum is classical.

The best alternatives to quantum are rated as following:
★★★★★  classical
★★★★★  shimano
★★★  photon
★★★  lumatek
★★★  focus
★★★  samsung focus
★★★  abu garcia
★★  classical mechanics
★★  mental dcuo
★★  celestial
★★  oasis
★★  newtonian
★  relativity
★  allure
★  neutron
★  surround
★  coppertop
★  neutron openstack
★  quanta
★  data domain
★  power armor
★  energizer lithium
★  phiten
  bohr model
  electricity dcuo
  intek
  pflueger
  finish powerball
  duracell coppertop
  overland
  hydrofarm
  powerball
  quickbooks enterprise
  time slice

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Speaking about quantum, one probably shouldn't forget about devstack.

Other search terms related to quantum and their ratings are:
★★★★★ devstack
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quantum
classical
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