At the risk of being publicly humiliated, let me say that I'm one of the very few people that actually REALLY MISSES McDonald's ill-fated ARCH DELUXE hamburger. From the peppercorn bacon to the premium bun, I thought it was top-notch for McDonald's.
But then again, what do I know, I also miss McDonald's Spanish omelet breakfast bagel, Taco Bell's chili cheese burrito, and even (gasp), the old PRE-Roy Rogers/Carls Jr Hardees 1/4 pound single cheesburger (w/ 2 slices of cheese, rare back then) that used to drip down your neck if you didn't have a napkin handy!
Arthur Treachers battered chicken (no, not the fish, but battered the same way).
Still nothing like it exactly.
Ginos Giant, the Gino Genie (actor Dom Deluise), & the original Kentucky Fried Chicken licensed under the strick supervision of Colonel Sanders himself. Sadly most of them eventually turned into Roy Rogers restaurants whose food made me physically ill (Marriot uses too much MSG)
Kenny Rogers Roasters, better than Boston Market by a mile even if Kenny Rogers didn't know what he was doing and also the best fast food macaroni and cheese ever invented! Nobody understands if you're gonna do mac & cheese it's NOT supposed to be day-old mush!
Oh, also Popeye's Cajun Sparkle seasoning (technically not discontinued or a purchased item, but few locations seem to have it anymore) and Bojangles "Dirty Rice" (also not discontinued, but there are none around much anymore and Popeyes imitation dirty rice is so inferior and dry)
Finally, Kentucky Nuggets are still available if you don't mind traveling to Maryland (see my other post).