The best replacement for db9 is vanquish.

The best alternatives to db9 are rated as following:
★★★★★  vanquish
★★★★★  vantage
★★★★  dbs
★★★  rs232
★★  db25
★★  v8 vantage
★★  pf9
★★  db380
★★  de9
★  cm9
★  r8
★  911
★  continental gt
★  xkr
★  f430
★  bentley continental gt
  granturismo
  gtr
  p938
  db7
  kel tec pf9
  bentley gt
  kahr cm9
  ferrari 360
  v12 vantage
  dbs difference
  sl55

Your alternative for db9 is not listed? Suggest!
Speaking about db9, one probably shouldn't forget about max232.

Other search terms related to db9 and their ratings are:
★★★★★ max232
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