Insufficient information in your initial post. You need to give the subject that you want to study at university and what type of university you are aiming for. it also depends what qualifications you already have.
General rule of thumb if you are aiming at studying sciences at degree level and have not got a substantial work related background, A levels will give you a better pre-degree level understanding. Some universities are not keen on Access courses for science related degrees, so if you want unrestricted choice go the A level route.
If you are aiming at a vocational degree, then there are Access courses tailored towards some of these degrees. The college where you do the course may have links with a local university to help with progression.
Access courses are generally okay for humanities related degrees. But it will depend on where you want to study.
Some will recommend A levels because you make it easier for the university admission tutor and potential future employers. But unless you are able to fast track your A level courses, it will take 2 academic years to complete. There can be more flexibility with A levels as you could take English and Maths A level, which would be harder to achieve on an Access course to the same depth.
Others will recommend an Access course because it only takes a year and gives you enough to gain admission.
1. What you want to do at university
2. What you need to gain admission on the course and place of your dreams.
3. What you can afford to fund in terms of A level or Access.
4. How long you want to study for at a pre-degree level.