Player of Games, Use of Weapons, and Look to Windward are the best of the lot, which i would recommend unhesitatingly.
Consider Phlebas is the irrelevant adventures of captain Changling McPoisonous.
Excession has an interesting concept, but most of the book is from the point of view of godlike super-intelligences and the fact that the author is made of meat starts to show very quickly.
Matter is basically a 700-page walking tour of the Culture universe. I'm alright with that, but if you insist on things happening or mattering, it might not be for you.
Surface Detail intentionally tries to squick you out in places, and it references an earlier Culture novel.