I think it depends on what you're getting out of the two players, and it's a tough question to ask at this moment. Hudler was a trade deadline rental this year and his value was a 2nd+. Meanwhile, Vanek was bought out by Minnesota after a couple of down years.
Historically, Vanek has been the better player, and his contract heading into 2017 is a higher salary. For what the Wings are looking for from Vanek/Hudler, I am happy to have Vanek because of the different type of game he brings from what the Red Wings currently have. Salary doesn't play a vital role in this conversation because they're both so similar and only for one year.
The question about Vanek is whether or not he is going to be able to bounce back from a down year, or if last year was really the beginning of a major regression for him.
My final thought on this is that I think they both picked teams that are going to be good matches for them. Hudler's offensive potential will be so much higher going to Dallas than it would be if he landed back in Detroit, imo.