> I found the underlying philosophy of the war much more interesting than the story.

This matches my experience. The Culture is fascinating to read about independent of the books. Here's a short essay by Ian M Banks (the author of the Culture series) about the Culture:

https://cultureandempire.com/html/culture.html

"Player of Games" is my favourite.

While I totally understand the intent of introducing the Culture from on outside point of view.

I think "Consider Phlebas" was not as enjoyable as some of the other books.

I have a hard time reading The Culture books as anything but a satirical condemnation of the current society. Which is not at all the position that Banks, in interviews, claims to take.

I thought Vernor Vinge's A Deepness in the Sky presented a much more sympathetic picture of a cosmopolitan trading culture, in its clash (and hybridization) with a conservative warrior culture. That book did make "the liberal capitalists" sympathetic.