The best replacement for gdb is dbx.

The best alternatives to gdb are rated as following:
★★★★★  dbx
★★★★  lldb
★★★★  gpx
★★★★  ddd
★★★  visual studio debugger
★★★  mdb
★★★  valgrind
★★  ida
★  windbg
★  gc8
★  shapefile
★  lldb debugger
★  ollydbg
  cdb

Your alternative for gdb is not listed? Suggest!
Speaking about gdb, one probably shouldn't forget about command line arguments.

Other search terms related to gdb and their ratings are:
★★★★★ command line arguments
★★★★★ emacs
★★★★★ core file
★★★ mpi
★★ debug symbols
★ command line options
★ stdin
★ xemacs
★ program arguments
★ ptrace
★ valgrind
core files
You have in mind a companion for gdb and it is not yet here? Propose!



Google Trends

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gdb
dbx
lldb