Already reported that other teams are looking to trade up. If you're taking McAvoy, you're insane not to trade down. At least to 6 or 7th , both teams rumored to be moving up. But really, you could probably move even further back. Some rankings have him outside the top 20.
Some scouts will look at Tkachuk with his 1st overall pick level production, 6'1 frame and tenacity around the net, and wonder "wtf are people smoking not drafting this kid?". You take McAvoy where gamebreakers are available and even if he is a quality defender people will remember you for that pick. McAvoy is going to be good but he is definitely not going to be an Ekblad or a Hedman, and maybe not even a Chychrun either.
Scouts feel the same way about Dubois. Accept that he's bigger, faster and a better two-way player than Tkachuk. I'm still very much on the Dubois train. If he ends up being capable of playing C in the NHL...that seriously tips the scales for him being a more valuable player than Tkachuk. It really seems like everything positive Tkachuk does on the ice happens around the opposition net. Dubois plays 200 ft.
As for trading down for a D...I'm probably a bit more inclined to move Eberle or RNH for a 20 something D with experience and a mid-first rounder. Then take a D with that mid-first. McAvoy could still be there.
I'd personally draft Dubois at 4.
Then try to move RNH to Minnesota for their first rounder at no.15 and Matt Dumba (RHD); or Detroit for no.16 and Brendan Smith (LHD) or Danny DeKeyser (LHD); or Carolina for no.13 and Jaccob Slavin (LHD) or Brett Pesce (RHD).
First target would be Dumba. Minny could really use RNH and Dumba is a RHD with a more proven offensive track record. I'd also still pursue Demers on the FA market.
Klefbom - Demers
Sekera - Dumba
Davidson - Fayne
Gryba/Pardy/no.7
Nurse, Reinhart, Oesterle, D. Simpson, Musil and Jones on the farm.