Gaucho before Shank for the kitchen. I've owned and used both for food prep. The Shank is too small to excel in the kitchen. The Gaucho is on the smaller side (of a real kitchen knife outside of a pairing knife) and is sporting too small of a guard for any real production kitchen work. However it (The Gaucho) does perform well when cutting smaller veggies e.g zucchini, carrots, tomatoes, even some smaller hearts of romaine. I'd use the Gaucho for prepping salads and sautés.
The Shank, on the other hand, in the right stock (1/8" or less) is an excellent blade for picnics and such. Cutting through the smaller logs of artesian charcuterie, cheeses and pickled favorites is something the Shank loves to do. It also looks handsome on a nice picnic table setup and is a conversation piece.
Both will serve you well as long as you don't go into it thinking you're buying the perfect kitchen tool.
Hope this helps.
Josiah