Programs between great faces/heels

What are great feuds that come to mind between two guys or teams that were amazing (and successful) as both heels and faces?

What comes to mind:

Jake Roberts vs Randy Savage (one of the most heated feuds ever, maybe even too short, should have culminated at WM8. Was there a heel Savage vs face Jake feud?)

Hulk Hogan vs Roddy Piper (worked both sides, 85 and 96/97)

Undertaker vs Mankind (long 96 feud, opposite alignments/sides in 98/99 again)

Hogan vs Savage (89 and 96-98)