The "best" answer is to take the job you like more, especially if you are still in school and you are going to apply to law school right away. When you are still a student, schools view your work experience more as an "extracurricular" activity. So they will not judge you too harshly for not having joined a ton of clubs and taken exotic unpaid internships (like working in senator so and so's office) if you have made serious time commitments to do stuff like supporting yourself.
The only situation where I could see a clear disadvantage to taking the restaurant job (assuming you would prefer the greater responsibility of management) is it you were going to delay applying for say a year. Then law schools may wonder about your interest in law and you won't have the option about writing about a law-related job. However, if you can show your interest in other ways, or have a really good personal story to tell in your essay it won't matter much, if at all. If anything, you'd stand out. It seems that everyone who is in the legal industry and is not yet a lawyer is applying to law school. I must know 10 people who are working as pseudo-paralegals who are applying, but I have not read one essay that has spun their experience into an interesting story. They all would have been happier working construction for a while.
If you plan on working for many years (more than two), then it is much more important to show advancement in your chosen field than it is to have a legal anything on your resume. Two years as a restaurant manager looks much more impressive and says worlds more about you than two years pushing papers.
For background, I worked for 5 years in a field unrelated to law and I have had many positive responses to my work experience.