The best replacement for powerpivot is powerview.

The best alternatives to powerpivot are rated as following:
★★★★★  powerview
★★★★  tableau
★★★  pivot
★★★  qlikview
★★★  power query
★★★  pivot table
★★★  ssas
★★  ssrs
★  tabular model
★  report builder
★  reporting services
★  ssas tabular
★  performancepoint
  pivottable
  power view
  powerbi
  spotfire

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Speaking about powerpivot, one probably shouldn't forget about excel 2013.

Other search terms related to powerpivot and their ratings are:
★★★★★ excel 2013
★★★★ ssas
★★★ excel 2010
★★★ power view
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