I started watching the Oilers in 1985, followed them closely from the 1986-87 season. Watched Mess a lot when he was a Ranger, too.
McDavid is clearly the better player on an individual level -- but, "individual level" doesn't mean much to me as hockey is never played/won by individuals. Fortunately, McDavid is also a better playmaker than Messier was, and a bit better at elevating teammates. Connor is also the superior skater / passer. Mess was elite at all those things, but Connor is better. (Goals-wise, they're probably about equal.)
You have to give this to McDavid with 5 scoring titles and 3 Hart trophies already, and possibly more to come. Mess "willed" the Oilers to victory at times (vs. NYI 1984; vs. Chicago 1990), but on a less dynamic club, McDavid has shown incredible ability to dominate in the playoffs, albeit in a much smaller sample.
Moog 1983? Fuhr/Moog 1984? Fuhr 1987/1988? Ranford 1990?
I would say the current Oilers and the 1990 Oilers (no Gretzky, no Coffey, no Fuhr) are at about the same talent level.