My pick for the most criminally underrated disc is the DX Cobra.
I picked one up a few months back at my local hardware store for a one disc round out of necessity and was completely dumbfounded how throwable it was. Let's face it, DX Cobras are basic and being basic is very unflattering. Noobs can't flick them, you won't see or hear your favorite pro mention them in an ITB, and DG marketing isn't aggressively shoving them in your face. Simply put, they're easily overlooked.
Why do I like them?
I can't put them on frozen ropes or effortless anny shots off the store shelf, they're cheap, and they're easily replaceable. I enjoy traveling and playing new courses, but I found myself taking less aggressive lines repeatedly for fear of losing my beloved perfectly seasoned premium understable mids to water hazards and or blind layouts with heavy rough. Ain't nobody got time for that.
In conclusion, people may think DX Cobras are like kissing your sister, but I think they're more like kissing your sister when you're from West Virginia.