It depends on what you want to study. Some think that BTECS are a waste of time and that BTEC students don't do as much work as an A level student. But no course will suit everyone. Teachers have often said "If you like to take exams, then A levels are for you, but if you like to do coursework and practical work then the BTEC is for you". It's not that simple: very few people like exams, but if you want to go down the more academic route it's best to stick to the traditional A Levels, whilst BTECs are good for more vocational and practical work. Remember to study a subject that you are passionate about - not because you think that is the 'easier' option.
There are three types of BTECs: National Award, which consists of six units/modules; National Certificate, which consists of 12 units/modules; and National Diploma, which consists of 18 units/modules. The pre-2011 qualifications are worth up to 360 UCAS Points (three As). However the post-2011 BTECs can now be worth up to 420 UCAS points (three A*s).
If you want to get into a university with a BTEC, you may have to have an additional qualification. Some universities accept BTECs; but if you are studying a BTEC in business, for example, you might need to have an A level on the side. Contrary to the myth that Russell Group universities do not accept BTEC qualifications, some do! It is unlikely that Oxford and Cambridge will accept them on their own (although apparently Cambridge do for some of their Engineering courses) but you can definitely get into very good RG universities such as The University of Manchester with a BTEC ND alone. If you are looking to study abroad, traditional A-levels are often better because they are internationally recognised.