Taking into account the simplicity of implementation, preformance and power, which would you say is better? It would be used in a game engine written in c++.

Lua wins on simplicity and performance, but Python wins on power.

It's difficult to compare the power of the two. Python has a lot more built-in support for various data structures, but both support metamethods to allow you to implement complex data structures yourself. In addition, Lua has an extremely simple yet powerful coroutine model which the main branch of Python has not yet fully replicated.

The prevailing opinion is that Lua has better performance, but I've yet to see any benchmarks that illustrate real-world applications, as opposed to thrashing the VM while computing fibonacci numbers.

Ok. Thanks. Since I've allready started using Lua I'll stick to it.