Here are my quick reactions. I will be doing some research and posting more in a few days. My older kid got four pins in his shoulder today so I won't be on this for a bit.
John Tarrant, Rector of Trinity, Pierre SD is a decent guy - one of a few who has been genuinely respectful and kind toward me in these times of conflict. He has helped his parish grow and is building some good joint ministry with Reservation congregations.
John Floberg has done some good bi-cultural mission building in North Dakota, including efforts to build fellowship among Native American men and grass roots efforts against alcohol abuse. He knows this part of the country and seems to enjoy it. Also a decent guy in my limited experience.
Douglas Dunn from Colorado serves a large parish and also provides mission leadership in a regional/rural setting. Don't know him personally. He is a native of SD.
Peter Stebinger is from Connecticut and I don't know much about him. I have heard that he has shown up as a nominee in other places - for a variety of reasons, that is a red flag.
But on the whole, it looks like the Nominating and Standing Committees sought out candidates who match the Diocesan profile and have credible (even fruitful) experience in settings like South Dakota.