I think the most interesting match is indeed Chelsea vs Munich. Both are in good condition for the start of this season. Another match could be Man City vs Napoli. I want to see how Napoli performs in the Champions League this season. They are clearly not a weak team, but what might be a bit of concern is Man City's performance, whether they can improve in the Champions League, or if their situation is not much different from last season.
Chelsea vs Bayern Munich is going to be an interesting encounter no that both teams look like they have found what is missing in their squad but to me Bayern Munich looks better looking at their current performance and the combination between Harry Kane and Luis Diaz. Napoli against Manchester City is not going to be an easy game for Napoli, Manchester City may be struggling but face a team that will be so dependent on Lukaku for them to such goals it's not going to be easy to defeat Pep Guardiola's men when they force attack on them.