I'm using AppCode for code editing and debugging, and XCode for practically everything else (project settings, designer, etc). These are features I'm using every single day:

* Buttons and toolbars - I don't use any. I have more or less consistent shortcuts between AppCode and XCode, and for less used features I'm using Cmd+Shift+A shortcut. It's an equivalent Cmd+Shift+P in Sublime and more powerful feature search than standard Cmd+? (which search only inside menus).

* Code navigation - put cursor on function, variable, property, whatever, press Alt+F7. You'll get a split panel, on the left are all places where function/variable/property is used (and you can filter it by read or write access), on the right is the preview panel, so you can see the code without changing cursor position in your main editor.

* Code navigation - Cmd + Ctrl + J to easily jump between function definition and declaration

* Refactoring - rename: yes, XCode have Rename, but AppCode rename is much more streamlined: put cursor on method/property name, press Ctrl+Cmd+E, change the name in place, as I'm typing every occurrence of the method/property name changes. I press Enter and the change is done, without modal dialog to review change. And rename works on protocols, too.

* Refactoring - Change Signature: in case I need to reorder function parameters. Put cursor on method name, Cmd+F6, reorder/rename parameters. And AppCode is smart enough to try to preserve natural flow of words - if the function is called saveContent:toFile, when I reorder params it will become saveToFile:content:

* Refactoring - easy promotion from ivar to property. And vice versa.

* Local history - I try to commit as often as possible, but I like an ability to see what I changed on the file in last couple of hours (with diff). And that option saved my ass couple of times.

* AppCode marks methods/properties that aren't used. I like to delete code. Less code is better. Very useful after refactoring.

* Better editor - I can split my editor horizontally/vertically however times I wish.

* Better editor - Shift + Ctrl + 1 - 9 will toggle quick bookmark. Ctrl + Alt + 1 - 9 will jump on the bookmark.

* Better editor - Cmd + Alt + UpArrow will expand selection. First sub-word (up to first "hump" in camel case) will be selected, then the whole word, then the next word, then the whole line... Cmd + Alt + DownArrow will go the other way.

* Better editor - Shift + Alt + Up/Down Arrow (or Shift + Alt + Click) will make multiple cursors, just like Sublime. Handy for changing lots of similar text lines.

* Better editor - select couple lines of code, Alt + Cmd + T will bring "Surround With..." popup. Press the mnemonic on the right to surround text with if, if/else, while, respondsToSelector, #ifdef,@try/@catch, etc, etc, etc. Time saver.

* Better editor - type SomeVeryLongClassNameIReallyHateToTypeTwice* var = alloc, press Tab, and AppCode will change "alloc" with [[SomeVeryLongClassNameIReallyHateToTypeTwice alloc] init]. Time saver.

* Better editor - Cmd+N will bring "Generate" popup where you can choose "Override method" or "Implement method", among other things. When the list of methods to implement/override is shown, you just type to narrow the selection. It's way faster to implement mandatory or optional delegate methods that way than to XCode-like start typing return value, then tableView: (for example) and picking the right method from the list.

Etc, etc - there's many more small things that good IDE ( * ) does to make programming more enjoyable. This list is just from top of my head.

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( * ) AppCode is just "good". For "very good" see Visual Studio + Resharper.