It's clear you need a strong center core and some game breaking wingers, depth etc, but forgetting about the forwards for once,
looking at the main top 6 defense on the past 5 Stanley Cup teams:
2017: pens D
Letang(INJ), Schultz (took lead), Maatta, Dumoulin, Cole, Daley, Hainsey.
2016: pens D
Letang (lead), Cole, Maatta, Daley, Dumoulin, Lovejoy, Schultz-wasn't used much that playoffs.
2015: blackhawks D
Keith (lead), Seabrook (dominate), Hjalmarsson, Oduya, Timonen, then split duties with Cumiskey/Rozsival/Rundblad.
2014: kings D
Doughty (lead), Martinez, Muzzin, Voynov, Greene, Mitchell. split duties Regehr/J.Schultz
2013: blackhawks D
Keith (lead), only Oduya provided some offense on D, Seabrook meh but two GWG and was a true leader for the team, Hjalmarsson, Leddy, Rozsival, all that top six D was healthy all through the playoffs.
So to break it down to create a sort of template of a Stanley Cup defense, you got the main #1 dman, a 2nd dman who can score, a couple two-way dmen and a couple defensive dmen.
Canucks in it's entire franchise history has not had that elusive #1 dman, nor a #1 OA draft pick.
Our current defense corps: Edler, Tanev, MDZ, Gudbranson, Stecher, Pouliot, Hutton, Biega, Sautner, Juolevi, Chatfield, Brisebois,
You can bash these comparison's to the Cup defense groups above all you want, but I think it's a semi fair comparison & a hope for the best look at it.
No clear number one dman lead, no backup scoring dman (the closest is Pouliot who could = Martinez) Pouliot this is his first real full NHL season.
But we got the two-way dmen in Edler = Seabrook and probably Juolevi could = Maatta or Muzzin.
And defensive dmen in Tanev = Hjalmarsson, plus Gudbranson = Willie Mitchell.
The alright dmen, but not dominating anything: MDZ=could be like Trevor Daley, and then there's Hutton and Stecher (one could breakout in the right situation).
Unknown: Sautner, Chatfield, Brisebois.
So in the perfect world using my template above for a Stanley Cup defense, we'd have:
#1 DMAN - Tanev
Edler - Pouliot
MDZ/Juolevi - Gudbranson
Meaning I'd gladly move out MDZ, Hutton and Stecher for picks/prospects/hockey deals, plus combine em with a few forwards that need to move to make roster space for the youth.
Now how the Canucks get that #1 DMAN is the million dollar question, ideally he'd be drafted just like the Pens with 6'0-201lbs Letang at #62 overall, Blackhawks with 6'1-192lbs Keith at #54 overall, and the Kings with 6'1-195lbs Doughty at #2 overall.
I think this team is primed for a blockbuster deal to move a massive amount of players like the Jets-Sabres deal awhile ago.
And you seen the Jets & Bruins they have a blend of vets and youth and everyone loves their teams retool/build/rebuild whatever.
Jets have big Byfuglien and Myers and the Bruins with 100 year old Chara, McAvoy and Krug.
So if you can't get that elusive #1 dman, you go with size and skill mix, why I'd look to get Bouchard this draft if you are outside the top 3.
A long time ago, a baseball player remarked: "If I owned a ballclub, I'd hire a $5,000 coach and a $15,000 scout."