On paper, an apprenticeship makes more sense. Your getting the qualification you need to become a solicitor whilst getting paid to do work experience. Also, your pretty much guaranteed a job at the firm once you've completed the apprenticeship.
Some people may find uni to be less stressful tho as they're not having to complete their degree alongside a full time job, and so they may feel they have a bit more freedom. But if your gonna need to be working anyway because of living costs or whatever then the apprenticeship helps to cover with that.
Im actually considering whether to do a legal apprenticeship or study law at uni myself. If i didn't care about the fact I might make new friends at uni and therefore have a better social life I would definitely consider doing an apprenticeship (assuming I could find one.)