gtags/ctags/etags/cscope support?

[Ergus]

Hi all:

Some days ago Stefan was talking about ebrowse but now it makes me
think.

Between global/gtags/ctags/etags/cscope which of them has been (|| will
be) better supported in emacs. Because there are many packages around
but I can't estimate their popularity.

Is it there any internal support for any of them within emacs? Is the
ggtags package actively maintained? 

Because I want to invest some time in one of them to improve the support
for tramp and ivy.

Which of them has more potential in your opinion?

Thanks in advance
Ergus