#1 John Cena

Perhaps the most fitting opponent albeit in another way for Angle in his final match would be John Cena.
Cena debuted ruthlessly and aggressively against the cocky angle in 2002. While Cena gave Angle a tough match, Angle ultimately prevailed.
Their was even that backstage scene of approval involving the Undertaker and Cena after the match.
Cena is a part-timer now but is still good in the ring. Like Styles, he might be over 40 but is still in phenomenal shape. He could help Angle along in the match and like Styles, it wouldn't be horrible if Cena lost because Cena doesn't need any putting over.
It would also be sort of a full circle moment since Angle's career would be finished by the man whom debuted against him nearly 20 years ago.
And when speaking about respect, Cena's motto is all about it. Who else would show the retiring legend any more respect? It would be an emotional moment for both men and a truly memorable moment for the WWE Universe.