However, spending often does not equal yield, you see Manchester City is the team that has spent much more money than everyone else but that just can't make the step forward, in fact if you look at the Premier League ranking it has gone backwards.
I think that at the moment the one with the best performance is Real Madrid
It is not possible to perform well in the Champions League by spending money alone. And we have seen the proof of this a few years ago. PSG spent a lot of money to build the squad. But even then the team could not do well in the Champions League. Experience is very important to do well in the Champions League. This season, PSG management did not spend much money on building the squad, but their performance is quite good.
You are right. Real Madrid is always very strong on the Champions League platform. However, Barcelona is also performing well on the Champions League platform this season. Also, Inter Milan and Munich are still in the competition.