This is my opinion only, I'm sure some have had different experiences - but:

Azure's success as a cloud provider is mostly a result of their sales team and having an existing relationship with non-technical leadership. "We already pay them for Office and Exchange, let's just buy this new 'cloud' thing from them too".

Azure is barely considered an option at all within tech companies, yet is surprisingly widely adopted by non-technical companies that don't know any better (ie, that don't have a technical / engineering voice or representation within leadership).

AWS = Likely technically the best, for now. Mostly unreasonable pricing, and less motivation to seriously negotiate given they are the 'default' cloud provider for most of the industry. Kind of feels like they have peaked though, and are slipping more recently. Inevitable, or bad leadership changes?

OCI = New-comer, attractive pricing and hungry for business. Might be able to avoid mistakes other providers have made? Reliability struggles though. Parent company has a bad reputation in some circles - but probably not with decision makers. Making huge (unwise?) investments - that will either come crashing down in 5 years, or seriously pay off. Layoffs, but going for massive growth...huh?

GCP = Notably different underlying technical choices than other providers. Folks are maybe a bit less pragmatic, and more academic. This helps them in unique services (Spanner?) but hurts in most other areas. They've matured, and are btwn AWS and OCI in reliability. They are probably not as hungry for business as they should be given how far behind they are.