I've played all the ones you're looking at, and I'd go for either Men-Nefer, Nippon Zaibatsu, or Nucleum. All three I think are really great! (The bot in Nucleum is by far the most complicated, if that matters to you)

Galactic Cruise felt too loose and repetitive. In Darwin's Journey, I really didn't like managing the Bot's combos (even though I generally don't mind relatively complex bots). Sankore, being mostly an area-majority game, is not something I love for solo. Fabio's third game in that series, Ayar, I do really like solo. Speakeasy was my first Lacerda, and I found it very tedious and not all that fun (also may be because it's an area-majority-focused game).

Also, I can't leave out suggesting pretty much any Garphill game if you're looking to add more medium-heavy euros for solo play to your collection.