The best replacement for fusion drive is ssd.

The best alternatives to fusion drive are rated as following:
★★★★★  ssd
★★★  flash storage
★★  flash storage imac
★★  ssd mac mini
★★  hard drive
★★  ata
★★  flash
★  ata drive
★  more ram
★  ssd imac
★  serial ata
★  ssd imac 2013
★  5400 rpm
★  solid state drive
★  flash drive
  seagate hybrid
  faster processor
  flash storage mac
  external ssd
  solid state
  serial ata drive

Your alternative for fusion drive is not listed? Suggest!
Speaking about fusion drive, one probably shouldn't forget about boot camp.

Other search terms related to fusion drive and their ratings are:
★★★★★ boot camp
bootcamp
You have in mind a companion for fusion drive and it is not yet here? Propose!



Google Trends

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fusion drive
ssd
flash storage