Honestly, I feel that rack pulls are better for back development/looks than dead lifts because you are able to target the back with far more weight, the tradeoff being less leg development and less functional strength.
I like deads from the floor at the very end of my back workout.
Basically activating every muscle fiber in your body if done under control and standing all the way up. No need to go super ridiculously heavy because total back of fried already. Both ways will fuck your back up if your already having issues with your spine.i actually think the deads from the floor are safer because lifters tend to get carried away with rack deads and load the damn bar up to much.
Doyle explained to me that he felt it was best to deadlift for strength (from the ground) once every 10 days for full recovery. He told me if your interested in building size a 3/4 deadlift is best as you can perform the exercise more often with less recovery time needed.
He benched and squatted once a week; he was a gentle giant and the most powerful man I ever met.
I love both, I like rack pulls because it literally puts more of the weight into my back and hamstrings ... Regular deads are my favorites.... But I think rack pulls and deficit deadlifts are two great tools people discredit too quickly.