I haven't really ever used XCode in a serious way nor do I use MacOS currently, but I have to give props to LLDB. It's commands are sometimes a bit clunky, but it is a lot easier to do stuff like setting breakpoints on C++ methods, searching across all loaded symbols, etc. than GDB on Linux. GDB is great so long as your code is C, but debugging C++ or other languages is kind of a mess.