It really depends on the exact booking classes. For instance, SK is interesting but not if you're flying LX/LH in N (as it won't earn any status miles).

TK, OZ, and A3 are other programs with low requirements, but again, flights in some of the lowest booking classes may not count towards status. It's interesting to note, though, that even the lowest booking classes on UA earn 50% status miles on all of A3, SK, TK, and OZ.

On a different note, I don't understand your statement
If you're making *G in any *A program, LX will let you board with business class. I realize your home airport ZRH is premium-heavy. But it's unlikely you'd board earlier (in percentile terms) when flying UA in Eco+.

I honestly don't know how problematic ZRH can be when it comes to scoring good seats (exit row etc.) that provide an experience equivalent or better to Eco+. As a *G, I usually don't have issues getting good seats for free. But my home base isn't ZRH. And again, I do realize ZRH has many, many flyers with a high elite status.