I assume there's a very strong element of personal taste here. I agree that Coke Zero is way, way better than Diet Coke, but it's still weird compared to regular Coke, to my taste anyway. I'd rather not drink soda than drink Coke Zero. I also don't have a giant attachment to drinking soda, so when I do it, I want to optimize for enjoyment.

I can't stand Coke Zero myself, better maybe, but still very weird aftertaste. I like those V8 Vanilla Raspberry energy drinks and I thought they were made with real sugar, until I added a can of it to a smoothie with real fruit.

"Strange, my smoothie tastes like it has artificial sugar now" I thought, come to find out they're made with Splenda and I couldn't tell before that.

I drink Diet Coke exclusively (as far as sodas) and (because it's what I'm used to, likely), I feel about Coke the same way you feel about Diet Code. It takes weird to me.

Personal taste. I love diet coke but don't like coke zero.