Let’s be honest: the simplest answer to the question in the title is probably ‘all of them’, so good is Joshua Kimmich for both Bayern Munich and Germany these days.
The Rottweil native, now 24, started out as a defensive midfielder, but in recent years has also played at centre-back and right-back, the position he is probably best known for among the wider footballing audience.
Kimmich seamlessly filled the vacant role for club and country following Philipp Lahm’s retirement in 2017 and in light of his quality and consistency there, it seems unfathomable that he might even consider playing anywhere else.
Watch: Kimmich under the tactical microscope
Just look at the raw facts: in 2018/19 alone, he was the only Bayern player not to miss a single minute of Bundesliga action. He helped the side keep 12 clean sheets, won over 53 per cent of all one-on-one duels and found a teammate with 91 per cent of his passes.
Arguably even more impressive were the 13 assists he provided over the course of the campaign, second only to Borussia Dortmund's Jadon Sancho and ahead of a number of attackers well established at international level. In 2017/18 it was 13 assists and one goal in 29 league outings. From right-back, he has won the Bundesliga, DFB Cup and 2017 Confederations Cup with Germany.
"He's a stroke of luck for Bayern," said former coach Jupp Heynckes of Kimmich in 2017. "He's going to have a big career ahead of him. His character is similar to that of the older players like Lahm, Bastian Schweinsteiger, Thomas Müller and Manuel Neuer."
Watch: A selection of Kimmich's best Bundesliga goals and assists
It is perhaps little wonder, then, that current Bayern boss Niko Kovac is reluctant to change a winning formula and move Kimmich from the right-back berth. "Josh has been playing very well in his position," the 47-year-old said in 2018/19. "I don't see any reason whatsoever to change that."
At the time, Kovac also cited the relative lack of cover at full-back - with just David Alaba and Rafinha otherwise available - as a reason not to tinker. However, in 2019/20 new signings Benjamin Pavard and Lucas Hernandez will be around, so Kovac will have more options at his disposal.
The new arrivals are both able to play in central defence too, but with Niklas Süle the first choice centre-back and Mats Hummels and Jerome Boateng also jostling for game time, it's unlikely that Kimmich would be moved inside. That is not as outrageous a thought as you might first think, as former coach Pep Guardiola played him there 17 teams during their one season together in 2015/16, describing him as "one of the best centre-backs in the world. He’s got absolutely everything.”
Kimmich's other 'best' position is in defensive midfield, where he operated at RB Leipzig in the 2014/15 season in the second division, prior to his transfer south.
And it is safe to say he is confident in his ability there: "I didn't make this transfer in the belief that I won't play. That wouldn't make any sense. I want to play as much as possible, even at Bayern. Bastian Schweinsteiger is a huge role model of mine, but as of next season we're going to be teammates and, to a certain extent, rivals."
For context, this was a previously unheard of 20-year-old throwing down the gauntlet to a midfielder who had played a leading role in Germany winning the World Cup the previous summer. Gulp.
Far from being youthful bravado, Kimmich has since provided the substance to back up his claim. In autumn last year, Germany coach Joachim Löw began playing him in defensive midfield and liked what he saw. "He's now played two games for us as a No.6 and he'll continue to do so because I'm very satisfied and he did everything well that is required in that position," the 59-year-old said in September 2018.
He reiterated that belief in March this year: "Joshua will continue to play as a holding midfielder with us, it has proven a successful move." And this is despite competition for places from the likes of Toni Kroos, Ilkay Gündogan, Leon Goretzka, Kai Havertz and Emre Can, among others.
Löw's faith in Kimmich is understandable. He has outstanding positional and tactical awareness, never shies away from a tackle, has an unshakeable will to win, is blessed with enviable stamina and rarely gives the ball away. What more could you want?
Germany are unbeaten in their last five games (three wins, two draws), with Kimmich starting each of those in defensive midfield. "I want to play in a central role so I can be involved and reach more players on the pitch," he told Sky.de after helping Germany beat the Netherlands 3-2 in European Championship qualifying in March.
"As a right-back, you’re not always 100 per cent involved in the game, which is quite different from the No.6 position. I've played there from an early age […] If I had to pick one position, then it’s the No.6. In the long-term that's where I'd like to play."
So where does that leave us? Perhaps the best answer to our original question should be left to one of the game's all-time greats, former Barcelona star Xavi Hernandez, who is a self-confessed Kimmich fan: "He can be one of the best players in world football in several positions, maybe he already is."