Welp, its 9 days later so idk how useful this is, but I kinda like Levi because once he's gone I can replace him with some other advisor unlike Baade, which removing him annoys the left of the party. If you want you can do Baade as well of course.
[Edit: I think Baade is good for the labor economic plan, but there is another advisor besides Levi who's good with repairing relations with the left]
Usually for a popular front I get Woytnsky (I just do the labor plan and let the communists do a no confidence motion, I can just reform the front after usually), Juhacz (to get a Weimar coalition in 1928 sometimes), and Levi for the aforementioned reason