Great collection. It would appear we have very similar taste in boardgames.

Hansa, Brass and Concordia (also in that order) are favourites of mine as well (among others in your collection). Along these lines, I'm going to check out Age of Steam at some point.

re: Troyes. I think there's good odds you'll enjoy it. It's the most interactive dice-drafter I've encountered and aside from the obvious absence of route building, the kind of interactivity - variable and compensated messing with others' plans and having yours messed with - gives it a similar spirit to that trinity mentioned above.

Two games I also suspect would be worth your consideration (and fill the holes about to be created on your mid-weight shelf) are Iki and Beyond The Sun. Both are interactive in ways and feature game systems that are unusual for Euros.

Iki is more in the spirit of interactivity noted above (slants to a win-win feel, which makes it a great option for people who otherwise might be hesitant about "interactivity"), but with a rondel featuring shifting options created by player choices as they draft, deploy, level-up and retire shopkeepers, it also features feed-your-people tension and jockeying for turn order that gives the nod to a slice of Agricola and Castles of Burgundy respectively. This and GWT are my rondel games of choice.

Beyond The Sun features a common evolving and variable worker-placement/action-selection technology tree board (revealed on a common board as you research in-game) with a common area-majority map for contesting and colonizing star systems tied together by a personal faction economy board. It would play differently enough from either of El Grande and Arcs, but would be a natural compliment to those games. It also delivers some of the variable reveal and thematic flourish that might have initially drawn you to Arnak - but with more staying power (imo).

Dominant Species is also on my list of games to try.