A free gingival graft is best. This can be accomplished nicely during a second stage, or uncovering surgery. Implants are placed using a submerged protocol. Then during the uncovering surgery, a free graft is used and guided with healing abutments. Impressions can usually be taken in 8-10 weeks.
If the patient is very cosmetically oriented and you think may object to a graft of a different color, the connective tissue graft is the best choice then. There is also less discomfort associated with a subepithelial connective tissue graft donor site.
As far as predictability, both are very predictable, since they would be placed on a vascular bed at the recipient site.
