Return on investment on mining on EC2

Hey,

I have a few tens of thousand of AWS credit that I would like to turn into $$.
Is Zcash the best currency to do it? What could be a plausible return on investment?

If someone is willing to help me do it, we might be able to work something out.
Let me know!

You are a little too late. Maybe try XMR or ZCOIN instead.