I mean it completely depends on what you want to do.
College is generally more vocational than sixth form and offers a wide variety of options. For example I knew people doing music performance, catering, art, photography, game design. You get to generally focus more on one thing.
Sixth form tends to be more academic focusing on A Levels/BTECs/IB but still allowing you to take a variety (3 or 4 subjects).
The different routes are suited better to different people but for me Sixth Form College was the best option. I got to do the A levels I wanted to get to the course I wanted at uni but still had more freedom and flexibility in my course than my friends at traditional sixth forms which suits my personality and way of learning better.