For sentimental value, nothing can improve upon the Canfield's Chocolate Fudge that my grandmother buys from Jewel-Osco.
Never seen this, but I like Cherry Vanilla Dr. Pepper a bunch if it's in light rotation. Dr. Pepper in any of its iterations causes some pretty quick taste bud fatigue, so I can drink a lot of it for like a week and then none for months. I'll never tire of Diet Barq's. It's ice-cold, complex, and cuts through the pizza you're eating like a sarsaparilla sword of Odin. There's really nothing else I can drink with that.
God I can't drink diet soda (besides the occasional Diet Dr. Pepper), I can taste the artificial sweetener giving me cancer.