Obviously free agency will likely inform what Buffalo’s needs are going into the draft, but I can see these being the major draft needs (due to $$$ to add vets at those positions, need to get better, need to get younger, and/or looking ahead).
CB - No way Buffalo will be able to sign Wallace for what he will get and Jackson isn’t really good enough to be full time CB2 IMO. Plus Tre likely won’t be back to 100% until late in the season at best. So they need to spend a 1 or 2 on a CB. I did see one person advocate for Joe Haden at a cheap price and I could go for that for a stopgap as well and then address CB in the next draft.
WR - Sanders won’t be back. Beasley is likely gone. Diggs is 29. McKenzie is an UFA. They need to add a young WR, preferably a slot receiver with some shiftiness and speed to beat zones.
DE - Buffalo has taken 3 swings at this over the last 2 years and none of those guys has panned out so far. Rousseau showed flashes and may put it together, but then need more youth and more pass rush production out of the position.
LB - This is both short term and long term. The Bills played with 2 LBers much of the season using a nickel as their base defense. But they need a 3rd LBer and, honestly, they need a guy to groom to replace Edmunds after this year. They’re already paying Milano a bunch of money and Edmunds is going to end up getting a pretty penny as a former 1st round pick, and while he’s shown flashes, he’s just not worth what he is going to get. Not with his flaws and not with what Buffalo asks if their linebackers.