Why have Coke when you can have Coke with less flavor?
No, but seriously, it's a rough comparison, because the flavors are completely different. Personally, I prefer the flavor of Dr Pepper over that of Coke, but that doesn't necessarily make it "better".
I would choose Dr. Pepper over Coke any time, unless I have had it a lot in a short period of time. But nothing can beat Pepsi Wild Cherry! But, yea, Dr. Pepper over Coke for me.