Both the Diamond Preferred MC and the Chase Slate are good cards, good for your BT needs. I have both and have used both.
That said, at least for me, CITI has been far more generous with initial CL and CLI than Chase. Chase Slate seems to be somewhat more conservative in their initial CL, but as always with all things credit, YMMV !
EDIT: One more advantage that CIT Diamond Preferred has over Chase Slate is, you can get it with the EMV Chip. Not available with Slate. Just something else to consider for the overall usefulness of the card, beyond the BT aspect.