Voracek > Simmonds, especially in their prime seasons, that's not really debatable.
However 30 year old Hayes at LW v 30 year old Voracek?
Hayes, 30 ES points, 45 total points in 50 games. CF 48.95%, CFrel +2.79, xGF 48.60%, xGFrel +2.50. 2.10 pp/60 (5x5)
Voracek, 39 ES points, 56 total points in 69 games. CF 52.99%, CFrel +2.68, xGF 51.86%, xGFrel +1.37. 2.36 pp/60.
Voracek had better raw metrics because he was on a more talented team, but relative metrics are pretty similar.
Hayes was also dragged down playing center. Last 40 games he jumps to CF 50.27%, xGF 51.05, since Dec 7, CF 51.42%, xGF 56.32%.
Playing LW has helped Hayes much in the same way it helped G.
Voracek at 31 still had 4x$8.25M, Hayes will have 3x$7M with a rising cap.