Most of this depends on your project's requirements. PaaS is much simpler for you as a developer, assuming your desired stack is supported. Caveat is it will l

Most of this depends on your project's requirements. PaaS is much simpler for you as a developer, assuming your desired stack is supported. Caveat is it will likely cost your client more. Although, it may not if you account for billable hours saved by not having to deal with IaaS. Depends on the project's scale and resource usage. With a small scale project, PaaS may be a wash or even cost less. Obviously it's good to expand your horizons learning new technologies. Doing so while under deadlines on someone else's dime, perhaps not as much. It's at least something to consider if there's very lax deadlines. How to bill it ethically is up to you and likely depends on a ton of factors. Using modern frameworks in languages you already know does seem to be a good compromise. Your learning curve there should be drastically lower than learning an entirely new stack from scratch. This is probably the safest route, and if you choose it I'd suggest learning new stacks on your own time regardless.