The best replacement for sonicwall is cisco.

The best alternatives to sonicwall are rated as following:
★★★★★  cisco
★★★★  watchguard
★★★★  fortinet
★★  juniper
★  checkpoint
★  barracuda
★  palo alto
★  pfsense
★  sophos utm
★  pix
★  untangle
★  cisco firewalls
★  zyxel
★  cisco asa
★  meraki
★  netscreen
  cisco asa 5505
  astaro
  cyberoam
  sophos
  firebox
  cisco vpn
  fortigate
  asa
  websense
  linksys
  cisco pix

Your alternative for sonicwall is not listed? Suggest!
Speaking about sonicwall, one probably shouldn't forget about content filtering.

Other search terms related to sonicwall and their ratings are:
★★★★★ content filtering
★★★ content filter
You have in mind a companion for sonicwall and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of sonicwall in all years. Click on graph for more.
sonicwall
cisco
watchguard