Choose between open declaration/implementation on Ctrl + click in IntelliJ IDEA

There is not a built-in option for this. You would need to configure a custom quick list to do such.

1. Open the Settings dialog and go to “Quick Lists” (It’s under “Appearance & Behavior” in IDEA 14)
2. Click the add button to the right of the middle pane
3. Give your list a name
4. Click the add button to the right of the far right pane (where is reads “no actions”)
5. Add the Go to Declaration action (Main Menu > Navigate > Go to Declaration)
6. Add the Go to Implementation(s) action (Main Menu > Navigate > Go to Implementation(s))
7. Click Apply
8. Go to Keymap in the settings
9. Under the “Quick List” node, find the Quick List you just created and map a short-cut (keyboard or mouse) to it. You can, of course, remap one of the shortcuts used by the Go to Declaration or the Go to Implementation(s) action
10. Click OK to close out of the settings and give it a try.

Note that in the quick list that opens, you will have numbers next to each action for quick selection.

Edit:
Adding a screenshot of final quick list for additional clarity