I don't know if Canucks should add much more to a Tanev package for Sam. Tanev is an actual top pairing D man. He might be a #2 or 3 on a very good team. He's the top guy in Van. The return for him should be far higher than what Benning paid for Gudbranson. Look at what the Coilers gave up for Larsson.
In no particular order.....
Erik Karlsson, Brent Burns, Kris Letang, Roman Josi, Mark Giordano, Dustin Byfuglien, Drew Doughty, Ryan Suter, Brent Seabrook, Victor Hedman, Kevin Shattenkirk, Duncan Keith, John Carlson, Alex Pietrangelo, Shea Weber, Aaron Ekblad, Anton Stralman, John Klingberg, PK Subban, Matt Niskanen, Jake Muzzin, Hampus Lindholm, Anton Stralman, Oliver Ekman-Larsson, Sami Vatanen, Tyson Barrie, Shayne Gotisbehere, Tyler Myers, Ryan McDonagh, Erik Johnson.....
That's not an exhaustive list, but it was very easy to come up with as 30 names I would take over Tanev. I understand that you said he might be a 2 or 3 on a good team, but right now Tanev doesn't even crack the top-100 in the NHL rankings for SAT% among defensemen. Granted, he only played 7 games before getting hurt, and SAT% is also reflective of the entire team, but I think we all over value Tanev to a degree. The guy is one of the smarter defensive guys in the league, but he contributes minimal offense, he has no physical game, and he's not a puck carrying defenseman by any stretch of the imagination.
Is he worth a top-6 forward? Yes. Evander Kane? Yes, but only because of Kane's baggage and injury history. Sam Reinhart? Maybe, but Sam still has potential that he hasn't reached, so you might be getting a guy who could end up playing top line center for your team.....Tanev, well you aren't getting anything that you don't already see.