In short. If your infrastructure is so small that it's about reserving 3 instances for a year. You should be running on Digital Ocean. It's much more simple and cheaper. You likely don't need the more advanced features from Google/Amazon.
If your infrastructure is in the hundred of VMs. Reserved instances are basically unusable, it's a NP complete problem to optimize capacity for a moving target. You're as likely to save 10% as to lose 20% on your reservations.
Last but not least. Reserved instances have many tricks and constraints that you'll only find out after you spend 10k on them, and can't go back.
In short. If your infrastructure is so small that it's about reserving 3 instances for a year. You should be running on Digital Ocean. It's much more simple and cheaper. You likely don't need the more advanced features from Google/Amazon.
If your infrastructure is in the hundred of VMs. Reserved instances are basically unusable, it's a NP complete problem to optimize capacity for a moving target. You're as likely to save 10% as to lose 20% on your reservations.
Last but not least. Reserved instances have many tricks and constraints that you'll only find out after you spend 10k on them, and can't go back.