I'm going to use current form as part of this because I think it's impossible to do it any other way.
Alisson
Robertson-Dias-Marquinhos-Walker
Verratti-Kante-KDB
Neymar-Lewa-Messi
Bench (essentially HM):
Keeper: Ederson, Oblak
CB: VVD, de Ligt
FB: Gosens, Zinchenko, Carvajal
DMF: Casemiro, Kimmich
CMF: FDJ
AMF: Pedri, Havertz
Wing: Mbappe, Salah
CF: Kane, Haaland
Manager: Pep. Staff: Zizou, Conte.
Keeper was tricky as I initially wanted Donnarumma in there, but I really value consistency and Donnar is there yet. Oblak is so so good but his distribution holds him back. Ederson is dinged because he slightly misplayed Di Maria's goal in the Copa finals. I believe Alisson had an injury or personal issues last year so I'm willing to give him a pass and I feel very confident with him net.
LB was one of the hardest positions and any of my 3 LBs could start. Robertson gets the nod for being at it longer and being slightly more physical than the other 2. Lots of other good options (Hernandez's, Digne, Mendy, etc.) left out.
CB was also brutal as Marquinhos was my only no doubter. VVD is on the bench because he was by far the best before injury. Dias gets the nod over de Ligt based on club season performance. Varane is one of my favorite players but he's slipped down a notch in a real way this season. Lots of young exciting players maybe ready to push into the true elite though, with Kounde, Upamecano, Gimenez, Skriniar, etc. all knocking.
RB is all Walker's at the moment, but there's a fun group just behind him. Carvajal makes the bench as he's the seasoned vet with the highest ceiling for 1 match, but he starts on the bench due to injuries. TAA, Cancelo, Pavard, James, and Bissaka are all close.
A wealth of riches at DMF and if you wanted to play a double pivot Kimmich is easily one of the 2 as he's the best of the 3 going forward. Casemiro brings height and physicality, and despite both of those guys being insanely good, I don't think it's even much of a question that the job is Kante's.
CMF is a weird one as there's some good players at the position but not a lot of settled ones. Verratti gets the nod for being excellent for club and turning it up another notch for the Euros. He was commanding in the MF. FDJ looks about ready to step into the #1 here over the next year or 2. Llorente, Valverde, and Barella may have something to say about that. If Pogba was a bit better for club, he'd be on the squad.
AMF was rather easy as no one holds a candle to KDB. Pedri has been wonderful and I can't wait to watch his career, but he's still just 18. Havertz also looks like he's ready to start delivering the goods but still might be a season or 2 away. HM to Bruno Fernandes and Dani Olmo.
Lots of interesting options at left wing, dominated by the PSG pair of Ney and Mbappe. Ney gets the nod because he can drop into MF when necessary and still has the ability to destabilize a defense. Hard to leave Mbappe on the bench but he can be shut down occasionally whereas Neymar can only be moved around, not stopped. If I was actually building a team, I might need Mbappe's speed on the field.
In the middle, it's Lewa by a hair over the remarkably consistent Kane and bigtime up and comer Haaland. Kane and Lewa are just about even for me, but Lewa's success with Bayern nudges him ahead.
On the RW, Messi gets one of his final starts at RW. Salah is only just behind him along with Gnabry and Mahrez. Lots of exciting young players in the future here with Sancho, Chiesa, and Pulisic!
The only manager that could corral this group is Zizou, as the threat of a KO headbutt will scare anyone into line. But Pep has shown that he's the best at getting the most of an all-time talented squad. I also had Zizou as the main manager first with Pep there to give him all the zany ideas, but ultimately I think Pep's longer resume wins out. I also didn't want a manager with a specific system like Klopp, Bielsa, or Poch. Simeone is too defensive. Same goes for Tuchel. Nagelsmann and Flick are close but I want to see more success from them first. Conte has shown tactical flexibility and has had great success, so he gets the opportunity to push Pep for expressiveness/absurdity on the touchline.