a good sign would be if the MA program has placed recent graduates in PhD programs that you would be interested in. Otherwise, in my view it's not necessarily the prestige of the MA that will matter, but how you use it to improve your PhD application. If it's a 2-yr program, you need to be focused on your PhD app from Day 1! Year 1 will fly, and by your Summer/Fall of Year 2 you will be actually doing your applications. Therefore in Year 1, you need to start narrowing down your interests and get your research questions situated in the literature. Use your seminar papers to get you to this point. From Day 1 make sure that the grad director knows that you want to move on to the doctoral level. Make sure you can take a class or two with profs that you would like to recommend you. Make sure to have a solid relationship with at least three profs in the dept that know your goals and research interests. Of course you will learn a lot and have a great intellectual experience too, but really to be blunt the MA will be more instrumental at this point.... Good luck!!