I have hired outsourcers from a lot of countries.
Phils are good, but you need to get them full time or they won't perform.
India are cheapest, but you need somebody with at least a STEM masters degree. And they say yes too much so you need to check their work until you find a good one.
Eastern Europe are solid, good and not as cheap as the others, but they will tell you no when you need to hear it.