He's a fringe number 1 Dman. He's as much a number 1 D as Turris is a number 1 C. Both kind of fit the description of their roles and even production but you won't win with either as the head of the charge. So therefore he isn't a number 1 D for me.
The current number 1 D's in the league
Karlsson
Doughty
Subban
Josi
Hedman
Giordano
Burns
Pietrangelo
Letang
Suter
McDonagh
Keith
Jones
OEL
Lindholm
Ekblad
Carlson
Byfuglien
Then you have those young guys who have potential to be legit number 1's but need a season or two more to be solidified with that title
Dahlin (already close)
Provorov(already close)
Werenski (already close)
Miro
Chabot
MacAvoy
Sergachev
Then you have those bordering number 1 D territory but more as offensive defenders who don't have a bit more pedigree to be considered flat out number 1s. Or defenders who are absolutely elite defensively but need to add a bit more offensive to be legit number 1's. IMPORTANT NOTE: These defenders can put up seasons like legit number 1 guys but they fluctuate and are not consistent enough to be considered established flat out number 1 guys but rather TOP PAIRING DEFENDERS.
Klingberg
Yandle
Rielly
Barrie
Vlasic
Seabrook
Faulk
Risto
E.Johnson
Fowler
Slavin
Brodie
and a few more
Come on man. I can understand somebody arguing the fact that Rielly may or may not be a top 15D because there's a lot of good d-men out there, but your Turris comparison is completely out to lunch. You're right that Turris is a fringe #1C, but using him as a comparison for Rielly is way off. The guy has never even scored 65 points in his career. I know it's early, but Rielly is leading the entire league in d-man scoring and is getting mentioned as one of the early Norris favorites:
NHL awards race: Early leaders for Hart, Vezina, Norris and more
When has Turris ever played close to this level? This isn't just a short sample size either. According to this article, last season he was one of only three d-men along with Doughty and Hedman to put up 50+ points, have a positive possession rating and play against top competition:
Toronto Maple Leafs: Is Morgan Rielly a True #1 Defenseman?
That's not an easy feat to accomplish and definitely not a crowd "fringe" #1D's are a part of. I get that some people have trouble putting these guys at that level until they see them do it for 5 straight seasons, but that's just refusing to accept reality until it's forced into you and doesn't make it any less true. Duncan Keith was an all world d-man for years, but for you to say that he's clearly better than a guy like Rielly today when most metrics for well over a season now clearly state the complete opposite is just sticking your head in the sand.