Who's the best hockey player in the world? Connor McDavid or Sidney Crosby?

That question will be front and centre again Tuesday, when McDavid and his struggling Edmonton Oilers hit the ice at the PPG Paints Arena in Pittsburgh to take on Crosby and the defending Stanley Cup champion Penguins.

Everyone from Wayne Gretzky to the fan in the street has weighed in on one side or the other.

Both players have been asked, many times. Both have answered, many times.

Crosby and McDavid provided pre-matchup quotes again Monday.

Fans love these debates. Because all you need is an opinion and, really, there's no way to be proven wrong.

Think, Beatles or Stones? Citizen Kane or The Godfather?

"Best" and "greatest" are subjective labels that can be applied to everything from heavyweight champions to hip-hop albums.

Such questions are mainly intellectual exercises, subject to personal preferences. But how do we measure one hockey player against another?

Casey Stengel once told his players, "All right, everybody line up alphabetically according to your height."

Not helpful, but pretty funny.

McDavid made his own headlines earlier this fall, when he said Crosby was still the best in the sport. But really, what else was he going to say?

Looking for a wider range opinions, the Associated Press recently asked 30 top NHL players to name the best in the world. Crosby got 21 votes, McDavid got six. Two players said they couldn't choose one over the other.

None of this is new.

Sportsnet magazine weighed back in October 2013, when it put a photo of McDavid on the cover accompanied by a screamer headline: "Better Than Crosby."

At the time, Crosby was 26. He'd already been in the NHL for eight seasons and had led the league in scoring, was named MVP, and had his name etched on the Stanley Cup. McDavid was 16 and was ripping it up in the Ontario Hockey League for the Erie Otters.

That headline made headlines of its own. But in his article, Gare Joyce was merely comparing a teenage McDavid to a teenage Crosby, quoting scouts who said Connor was ahead of Sidney if you looked at both players at the same stage in their development.

In April 2015, two months before the Oilers won the lottery (again) and selected McDavid first overall in the NHL entry draft, Sportsnet published another story with another audacious headline: "Gretzky Agrees: McDavid is better than Crosby."

It was sort of true, sort of not quite. That story was, in part, based on a statement Gretzky made during an interview with Jim Matheson of the Edmonton Journal.

Gretzky told the sportswriter that McDavid was "as good as I've seen in the last 30 years. The best player to come into the league in the last 30 years."

That part of the statement was quoted most widely. Because "in the last 30 years" seemed to indicate that, in The Great One's opinion, McDavid was better than Crosby.

But Gretzky wasn't finished there. He followed up, in the same interview, by clarifying that McDavid was "the best to come along since [Mario] Lemieux and [Sidney] Crosby."

Which brings us back to the question: how do you measure one player against another? And why bother?

Hip Check: McDavid and Crosby take the same ice for the first time this season1:08

Does it even matter right now?

The Oilers and Penguins faced each other twice last season. Pittsburgh won both. McDavid finished the season with 30 goals and 70 assists and easily won the scoring race. Crosby led the league with 44 goals.

Crosby is 30 years old and still in his prime. At 20, McDavid hasn't reached his.

Crosby scored 102 points in his rookie season and raised his total to 120 in his second year. McDavid missed half his rookie season with a broken clavicle. But he still managed 48 points, which translates to 87 points for a full season.

OK. Well, 102 points as a rookie is better than 87, right?

Not according to Dom Luszczyszyn, one of the best hockey analytics writers out there. He now works for The Athletic, but last spring, when he was with The Hockey News, he crunched the numbers for Crosby and McDavid and put them in context. Based on the way league scoring has dipped in the past decade, Luszczyszyn found that Crosby's 102-point rookie season would translate to 85 points today.

So, McDavid's scoring rate as a rookie was every-so-slightly better.

But hockey is a team sport. Stick a microphone in front of any player's face and he'll tell you that individual numbers and trophies mean next to nothing.

Team success is all they care about. In other words, winning.

Crosby was in his fourth season when he first got his name on the Stanley Cup. He won his second Cup in 2015-16 and captured his third last season.

McDavid led the Oilers into their first post-season in a decade last spring, where they fell in the second round to the Anaheim Ducks.

Which brings us back, yet again, to the original question: who's the best hockey player in the world?

Answer: It's way too early to tell.

Really, it will be up to the history books to decide. When Crosby and McDavid have both hung up their skates, then maybe we can look back objectively and try to find an answer.

In the meantime, who the heck really cares?

The simple fact is, this is a great time to be an NHL fan. Tonight, the two guys everybody's talking about will go head to head.

'This is a great time to be an NHL fan. Tonight, the two guys everybody's talking about will go head to head.' - Rick McConnell

The game won't settle the debate.

Because it can't be settled, not now and perhaps never.

The Hockey News was at it again recently. In the "Great Debates" issue, writer Ryan Kennedy said: "If the parameters of the argument are Best Player Right Now, then there is no argument. Sidney Crosby is the best player in the world."

Kennedy said much more, but summed up  his argument this way: "There's just no comparison here … Crosby would shut down McDavid head-to-head."

Writer Ken Campbell took the other side. He created a pretend scenario where George McPhee, GM of the league's new franchise in Las Vegas, got the chance to pick one player to build a team around. "And who do you think he would choose?" Campbell wrote.

"Well, it would be Connor McDavid, of course. Now that's not necessarily saying that McDavid is the best player in the NHL. It's more a prediction that he will be."

Earlier this year, Gretzky himself weighed in again. In January, the Oilers executive said he'd spoken to McDavid and had told the young superstar that if he wanted the title he'd have to wrestle it away from the current king.

"Crosby is the best player in the game, and he has earned that mantle," Gretzky said. "Connor sees him in his vision, and that's what makes the game wonderful is that if you want to be the best player, and Crosby is the best player, then you have to earn your stripes.

"Until someone knocks [Crosby] off the castle, that's how it's going to be."

It's certainly not the final word on the subject.

But it'll do.

For now.

@WriterMcConnell

​rick.mcconnell@cbc.ca