I would actually suggest you use either a journey or a triggered send, depending on your needs.
If you just want to send a one-time email, then use a triggered send. It's basically an Apex trigger on whichever object you configure which sends an email through Marketing cloud when it fires .
Yout have some more information on how to create it in the official documentation here.
On the other hand, if you want to do some further operations after that email, like updating some records in Sales Cloud or simply sending some follow up emails, then I recommend you use a Journey. The journey builder is somewhat complex, so instead of explaining here how to configure it, I'll also forward you to the documentation here.
In any case, what I completely discourage is to hard-code it everything in AMPScript since it's not scalable. AMPScript is useful, but it must be used carefully because it can end up making the emails very complicated. If it's something you can do with the standard integrations, like the Marketing Cloud Connector, then I advise that.