#1 France

The reigning World Cup winners are also absolute favorites to win the U21 Euros crown. The quality they possess is genuinely ridiculous. Even the players that haven't been called up like Caquaret, Todibo and Saliba are phenomenal and would get into almost all other teams starting lineups.
In Illan Meslier and Alban Lafont, France has two of the best U21 keepers in the world. Their centre-backs consist of Jules Kounde (who in my humble opinion is the best player in the tournament), Wesley Fofana, Ibrahima Konate and Benoit Badiashile.
That's four centre-backs who would get called up for the senior teams in most countries. The midfield is insane as well.

The crux is formed by Matteo Guendozi, Boubacar Kamara, Eduardo Camavinga, Boubacary Soumare and Monaco's latest sensation Aurelien Tchouameni. Like the keepers and the defense, their midfield is also the best in the tournament.
Odsonne Edouard, Jonathan Ikone and the in-form Amine Gouiri round off the forward line. The absence of Houssem Aouar and Mousa Diaby would hurt any side but with the strength of this France team, that looks unlikely.