I would definitely recommend Reds over Blacks. All of my Reds are very friendly, and I have had bad experience with a Black SL female that was super stand-offish and agressive. Of course, like others have mentioned, you can have different strains developing in different hatcheries. THe first time I saw someone post that their Reds were mean, I almost fainted from shock! Mine are so sweet and inquisitive, and have distinct personalities.
Just the other day, my biggest hen, Darla, hopped into my lap while I sat on the patio, proceeded to bawk up a storm like she was sharing the day's gossip, then primly hopped to the ground and wandered away. I was laughing so hard!
I personally think that my hens are either RIR/Cuckoo Marans, or HR/Cuckoo Marans. SOme of them lay super dark eggs that are terracotta in color.