One global fund is already diversified enough for all practical reasons. Your investment will be more successful if you earn and save more, rather then trying to play the markets.
I will dump few more funds that you should consider. You won’t be wrong with any of them.
Thanks! Yes fully agree.
All the best.
I think no one here would be able to tell you which ETF would be best performing in coming years because it’s one of the most difficult task. Often there is a tendency to look at past returns as proxy for future which can be completely irrelevant.
However expected returns are estimated by some research groups on continuous basis for various type of asset classes. One such publication from Vanguard is at link below. Hope it helps you decide
Thank you! I was more seeking feedback from you and diverse point of views rather than strictly recommendations on the best ETFs to invest in because as you said this is a difficult task.
Once again, I really appreciate your insights!
Well you did ask for recommendations 
Anyway, most important is to buy something diversified with low fees, that’s it. Of course you can optimize for taxes and fees, convenience or personal preferences, but that’s not the main concern to me.
You already specified you do want a long-term investment and don’t need to money now to grow your business or pay your rent. That’s why the personal situation matters for a recommendations.
Final thought, I assume you have checked the tax situation in Portugal? There could be some specifics that impact your product choice.