Hi @Best, Damani J ,
Both methods can use Hybrid Benefits for cost-savings as long as you have a Server OS License for the Virtual Machine you deploy.
You can use an MSDN Subscription for the deployment costs no matter which method, but licensing may need to be separate if you want to purchase one to use with Hybrid Benefits. Marketplace Deployments offer pre-built server setups/environments, where bringing a custom Image may just be your own modified environment to deploy into a Virtual Machine.
Users often initially deploy a Marketplace Image to make the changes they need, then copy that Image to deploy into new Virtual Machines, or Scale Sets.