The best replacement for f3 is f6.

The best alternatives to f3 are rated as following:
★★★★★  f6
★★★★  l9
★★★★  f5
★★★  c300
★★★  f4
★★  f3hp
★★  f4i
★★  fs700
★★  f5 skybox
★  fs100
★  f2
★  nex 5n
★  c100
★  af100
★  fnv
★  v911
★  3n
★  fm2
★  fm3a
★  f3r
★  fa
★  lg optimus l9
★  5n
★  panasonic af100
★  gp3
★  lg optimus f6
★  sentinel x400
★  caviar black
★  dreambox
  f100
  f7
  fe
  samsung galaxy victory
  canon f1
  alexa
  fe2
  lg l9
  675r
  c5
  wd black
  nikon j1
  canon new f1

Your alternative for f3 is not listed? Suggest!
Speaking about f3, one probably shouldn't forget about pix 240.

Other search terms related to f3 and their ratings are:
★★★★★ pix 240
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Google Trends

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