I have Hopkins and Metcalf in both of my leagues..... Auction wise they were the best value for top 5 talent, and for some reason people aren't on them as much because they aren't the "New Shiny Toys".
I honestly don't think you can go wrong with anyone of them. Hopkins could easily score closer to 10 tds this year, which is more of his norm after a full off-season with Murray. Hopkins has a floor of 100 receptions, and 1200 yards, and always the potential to be the top WR
Metcalf to me is the next possible Calvin Johnson. He has the potential for 15 tds, and honestly was on his way there last year until the Seahawks offensive coordinator completely messed up their offense the 2nd half of the season. (First 8 games last year 43 receptions, 788 yards, and 8 Tds, he also had one fumbled in the endzone because he celebrated too early, which would have been 9 Tds through first 8 games) The potential is there for him to be #1 overall, and I am not sure why more people aren't all over him this year in his 3rd year.
Ridley definitely has the potential to be #1 overall, and you can't go wrong with him just due to sheer volume. I think the Falcons will also have a lot of garbage time points as they will be playing from behind.