It is hard to say which was worse. Each was worse in some ways than the other. Neither is/was much of a president.
The Carter years though, were darker. I have trouble explaining just HOW dark to people who didn't live through it. I was young, a teenager, but I remember. I particularly remember the adults I looked to at the time, how grim they were, how worried and fearful, and how they struggled against despair. After the chaos of the 60s and the war and civil unrest, followed by the scandal of Watergate, things were looking grim. So many things came together at once (supposed energy crisis, Soviet expansion and threats from them and the Chinese, the nuclear Sword of Damocles hanging over our heads and doubts that Carter would retaliate leaving us looking weak, hostage crisis in Iran cannot be understated, the "Misery Index" and recession, and more) to rob the people of hope and optimism, and we had no leadership helping us get past that.
Every time our leaders appeared on TV, they looked grim and worn, and sounded overwhelmed and exhausted, shoulders slumped, and spoke as if America was already finished.
Then came Ronald Reagan, and he was standing up straight and proud and smiling... his tone, his face, his manner all projected a confidence that was nothing short of ASTONISHING in those VERY dark times, when most people were beginning to believe the End was upon us. He told us that No, this was not the end of America... just the beginning. "I have a vision of a shining city on a hill, where it is not sunset in America, but only morning."
He gave hope where hope seemed gone.
Read this speech and maybe you'll understand better why so many people loved Reagan... not because he was the perfect conservative President, but because he brought hope to a people who had all but abandoned hope.