It will depend on whether you are better at coursework or exams. A levels is mostly exam based whereas BTEC is coursework based throughout the year. Personally I think that BTEC's are easier and therefore this would make it easier with getting into uni. Just be careful though as a small amount of uni's might not accept BTEC's. I got accepted to all of my universities but i decided to go to Nottingham Trent.
Hope this helps, if you have anymore questions just let me know