If Manchester City, Real Madrid and Bayern Munich are the top three clubs in the Champions League, then I think one more club should be added here and that is Arsenal. Maybe we don't see such a good performance from Arsenal in the Champions League, that's why we can't put this team in the list of favorite teams.
If you add Arsenal to the list, you will have to consider to add more clubs to it. Arsenal is good but not like a very strong team with too much better competitiveness than many clubs around Europe. Arsenal are not much better than Barcelona and if you bring this question up for discussion, there will not come to any universal conclusion. It means these clubs are not different too much in quality and competitiveness.
Injury problems are unwelcome and can happen to every club, but Arsenal's players are known to have the most injuries every season.
Injury issue was most commonly in era of Arsene Wenger and several previous years. It seems that in last two seasons, injury is no longer biggest problem in Arsenal and it helps them to play impressive in Premier League and Champions League.