I LOVE Daryl so f'n much! BUT Carl (even tho he had that slip up with that guy from wood berry in the woods that he shot after the dude surrendered). I think he's learned from his mistakes. I think Daryl is too aggressive sometimes and loses his composure. Especially after this season of TWD, Carl definitely proved his capability, how he covered Rick's a**
Even though Carl is a kid, he is strong and is willing to do whatever it takes to defend the group. He learned from Rick, so he knows how to get it done. He is willing to fight for the safety of the group and has been a big part getting them to where they are now.
Personally, I love Darrell. He kicks butt, never gets beat, and has been with the group since the first season. But same with Carl. He learned from the best. Rick taught him the values of life and that others come first. Darrell would make a great leader, but I think Carl is the man for the job.
Besides being too young to influence a group of adults he has also a deranged side to him. He shot another kid in cold blood when the other was going to surrender. He claimed he 'Did what he had to do', but he really didn't have to. What he did was wrong, and it would be worrying for someone like that making decisions for the group. He is going to that crazy place that Rick went. Cold and uncompassionate.
There is no way Carl could lead on The Walking Dead. He does not have the right skills or personality to be a leader. Darrell was the same way at the begining of the show but at this point he has changed and could easily lead the group if Rick dies.