Ceteris paribus, it is definitely good to have research experience. If it is a top journal/conference, then it will be a plus.
Some good things that come with a research work:
1. you can write about the work and experience in your
SOP
2. you can talk about it during discussions with faculty in the school that you are applying to
3. your co-author will have something meaningful to write about in his recommendation for you
Also, remember to touch base with profs that you meet at the conference. It will be helpful to your chance.