If It's between Lanning and Kiffin, I'd have to go with Lanning.
Kiffin is still a bit too much of loose cannon in my opinion, Lanning is a risk as well, but he understands the type of system Saban has and he's obviously competent.
His three years at Georgia (as DC) they were #1, #17 (.6 behind Alabama), #1 in scoring defense. His two years at Oregon he's gone 10-2 and 12-2 and used the portal well.
I'm not as down on Dabo as some people here are, there's only so many coaches out there that know how to win it all and clearly he does. The big issue is probably that he didn't accept the job when Saban hired him, so he didn't get to learn under Saban.
He'd have to adapt to Alabama's way of doing things somewhat, and to the current climate of college football and I'm not sure how willing he'd be to do that though. I'm just not sure what Kiffin or Sark did to make people think they have a better resume than Dabo, because clearly they don't despite both coaching at top tier schools.