We have moved legacy Windows workloads onto both AWS and Azure, sometimes for clients in the same industry with nearly identical applications. So we get the "which cloud?" question a lot, usually asked as though it has a secret correct answer we might share if pressed.
Here is the answer we give: for a legacy Windows and ColdFusion estate, both platforms are fully capable, the workload will not notice the difference, and the decision should be made on grounds that have almost nothing to do with the feature comparison pages. What follows are the grounds that actually decide it.
Who operates this after the migration?
The single most predictive question. A cloud environment is operated by someone: your internal IT, a managed service provider, or a partner like us. Wherever that operating muscle already lives is a heavy thumb on the scale.
If your organization runs on Microsoft tooling, your identity is in Entra ID, and your MSP provisions everything with Azure runbooks, choosing AWS means either retraining that muscle or splitting your estate across two operating models. Both are real ongoing costs that dwarf any pricing delta. The mirror image is equally true: an organization with AWS competence in-house should need a strong reason to put Windows workloads anywhere else, and "it's Microsoft software" is not one. Windows Server and SQL Server run well on AWS and have for years.
In our experience, when the honest answer to "who operates this?" is an MSP, the MSP's platform is usually the right platform. Fighting your own operator is a bad trade.
Licensing: real money, boring details
Licensing is where a genuine cost difference can live, and it is resolutely unglamorous.
SQL Server licensing dominates the math for most legacy estates; the database licenses often cost more than the compute under them. Microsoft's licensing terms have at times favored its own cloud for certain license mobility scenarios, and the rules shift enough that they should be verified against current terms during planning rather than assumed from a blog post, including this one. What matters is that someone on the project actually runs the licensing comparison for your specific SQL Server editions and core counts. We have seen the answer swing the platform decision, and we have seen it swing project budgets by more than the entire migration fee when nobody ran it.
ColdFusion licensing, by contrast, is platform-neutral: you bring your license either way. Just confirm edition and instance counts against the target architecture before install week, a lesson that generalizes to every licensed component in the estate.
The parts that are identical everywhere
Worth saying plainly, because vendors will not: the hard parts of a legacy migration are the same on both clouds. The dependency inventory. The database migration and its downtime window. DNS TTLs and cutover sequencing. The reporting stack that turns out to be welded to a specific SQL Server version. Testing by IP before the DNS swing. Rollback posture and how long the legacy environment stays alive. We keep a field checklist of these, and not one item on it changes based on the cloud logo.
This is the real reason the platform question matters less than people want it to: platform choice cannot buy you out of migration discipline, and migration discipline succeeds on either platform.
A note on the edge stack
One asymmetry we have hit in practice: organizations sometimes arrive with a third vendor at the edge, a CDN or WAF layer, that predates any cloud decision and misbehaves in ways nobody can see into. Consolidating the edge onto the same platform as the compute (CloudFront and WAF on AWS, Front Door on Azure) buys you one vendor's logs, one support channel, and one throat to choke when requests go missing. It is not mandatory, but when you are already paying for a migration, collapsing an opaque edge layer into the platform you are moving to is often the cheapest reliability win in the project.
How to decide in one meeting
Put four answers on a whiteboard: who operates the estate afterward, what the SQL Server licensing comparison says for your actual core counts, where your identity and security tooling already live, and whether any existing vendor relationship (MSP, EA agreement, support contract) creates a real constraint. In our experience the platform picks itself by the second or third answer, and the meeting can move on to the part that determines success, which is the migration plan.
If you have a Windows or ColdFusion estate headed for the cloud and want the licensing math and the migration plan done by people who have run it on both platforms, see our AWS and ColdFusion migration practices, or start a conversation.