The best replacement for 600t is 650d.

The best alternatives to 600t are rated as following:
★★★★★  650d
★★★★★  c70
★★★★  500r
★★★★  haf 922
★★★  750d
★★★  540 air
★★★  760t
★★  haf x
★★  550d
★★  switch 810
★★  haf xm
★  800d
★  phantom 410
  storm stryker
  nzxt phantom

Your alternative for 600t is not listed? Suggest!
Speaking about 600t, one probably shouldn't forget about h100i.

Other search terms related to 600t and their ratings are:
★★★★★ h100i
★★★ h80i
★★ h100
You have in mind a companion for 600t and it is not yet here? Propose!



Google Trends

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600t
650d
c70