If these are new what often happens when you ask about new plants is that nobody has anything to say because there is no experience going back any serious length of time.

Sweetheart gets some very good reviews........Razz not so much (not at all sure of the attraction of a blueberry that tastes like a raspberry!). If you have the room, both may be worth trying out but since this is a great blueberry growing climate overall, I'm not sure I'd restrict my selection to just these two.