The best replacement for nspire is nspire cas.

The best alternatives to nspire are rated as following:
★★★★★  nspire cas
★★★★★  89
★★★★★  ti 84
★★★  ti-89
★★★  ti nspire cas
★★★  ti 89
★★  84
★★  nspire cx
★★  ti 84 plus
★  ti-84 plus
★  cas
★  hp 50g
★  prizm
★  ti 89 titanium
★  50g
★  ti 84 plus silver edition
★  84 plus
★  hp prime
★  ti 83
★  ti nspire cx
  hp50g
  hp 50
  ti titanium
  classpad
  voyage 200
  ti inspire cx
  ti-84

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Speaking about nspire, one probably shouldn't forget about ti 84 plus keypad.

Other search terms related to nspire and their ratings are:
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nspire
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