[the-anarchist]

This depends on many details and there's no general answer to your question. Also, Estonia and Romania do not only offer easier incorporation, but are an overall better fit for businesses like the one presented here (at least from the limited information that I was able to gather on it) due a higher flexibility, more favorable taxes, and fewer regulations in general.

Since you're mentioning a GmbH I'm assuming you're based in either Switzerland, Germany or Austria. Generally speaking, regulation and tax codes in these countries have made it very unfavorable to operate any foreign entity, unless there's a fair amount of substance and structure in the target jurisdiction that make it worthwhile.

However, it is important to mention that while it is often the "natural" thing to do, operating a business in the same country that the founder is based in is almost never ideal from a regulatory and tax perspective. Unforunately, though, proper planning and execution of advanced structures is usually not something the average startup founder is a) primarily interested in and b) able to afford.

Given the other comments in this thread mentioning the founder's rather left-leaning political views, I assume that regulatory and, specifically, tax optimization were none of the founder's main goals to begin with.