The best replacement for 5x5 is 3x5.

The best alternatives to 5x5 are rated as following:
★★★★★  3x5
★★★★  3x8
★★★★  3x10
★★  starting strength
★★  3x3
★★  pyramid
★★  4x8
★★  10x10
★  ss
★  5/3/1
★  4x6
★  5x3
★  phat
★  531
★  rpt
★  gvt
★  5 3 1
★  hst
★  split routine
★  8x3
★  wendler
★  5 x 3
  hypertrophy
  5x3x1
  5x127
  6x6
  20 rep squats
  rippetoe
  5x4.75
  westside
  5\/3\/1
  10x3
  german volume training
  8x8
  4x4
  reverse pyramid

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Speaking about 5x5, one probably shouldn't forget about hypertrophy.

Other search terms related to 5x5 and their ratings are:
★★★★★ hypertrophy
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