Louisiana has the most solid Democratic base, but I also feel like it's become really inelastic and it's going to be really hard for a Democrat to reach 50%. I feel like Arkansas is still more open to "the right kind" of Democrat.
My reason to choose Louisiana is that I think both states are de facto impossible to win for the Democrats in a statewide election, but since Louisiana has a higher floor Arkansas must be considered "harder".
Looking forward to an answer from someone in the know. Miles may be the best bid for a qualified evaluation.