I am not the person to whom you replied, but the feature I use most often in Xcode is Go To Definition (with command-click). This integrates with clang, so it knows how to navigate templates, overloads, etc. It also integrates with the build system, so it knows the correct header search paths, preprocessor macros, etc.
I imagine there are some plugins available for vi and emacs that try to provide these features, but I would guess they require some configuration and won't work as reliably.
Whether they work as reliably depends on the language. Emacs + Slime for Common Lisp is fine. Nowadays there's luckily a lot of editor / IDE independent tools like Jedi, ycmd, eclim which improves the situation for Emacs and Vim considerably.
C++ has always been had issues but for me it's good enough especially since I move between languages and OSes a lot. If I was just doing C# on Windows I would probably use an IDE tuned for it.
I find that it depends on what kind of languages you work in. Boilerplate-y languages like Java require way too much hand-holding to be nice to do in an editor. On the other hand, Haskell/OCaml in Vim are fairly nice with the right plugins, as long as you don't mind refactoring via sed.
For "go to definition" I use either ctags or cscope. Cscope can work as a front-end and launch -whatever- editor you want. In nvi, I have good interfaces to both cscope and ctags, and I believe most vi clones have ctags interfaces, and emacs has etags.
I imagine there are some plugins available for vi and emacs that try to provide these features, but I would guess they require some configuration and won't work as reliably.