The best replacement for asa 5505 is sonicwall.

The best alternatives to asa 5505 are rated as following:
★★★★★  sonicwall
★★★  pix 515e
★★★  pix 501
★★  1841
★★  ssg 5
★★  881
  sa 540
  pix
  1921

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Speaking about asa 5505, one probably shouldn't forget about dual isp.

Other search terms related to asa 5505 and their ratings are:
★★★★★ dual isp
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asa 5505
sonicwall
pix 515e