I’ve seen people go with IBM Cloud because their salespeople were willing to discount more heavily than AWS/GCP/Azure were. Tier 2 players can be hungrier for your business than tier 1 are. And here I’m talking about completely mainstream workloads (Linux, K8S, etc)

Separately from that, if you are trying to move certain types of non-mainstream IBM workloads to cloud (AIX, IBM i, z/OS) then IBM is tier 1 in that case