I apply PPF (paint protection film) for a living and get to work on the most exclusive cars on the planet. Our film is clear and doesn't alter the look of your original paint.
Wrapping a car is a very different process to what we do however I come into contact with it on a daily basis.
If you go cheap you will have people using shit film which will damage and show the paint through from underneath with the smallest lowest speed stone chip, they will probably trim the film on the car and when it's removed you will have knife marks all over it.
If you go expensive £3000+ for a full car, you will get the best, hardest wearing, colour consistent film there is. The downside of this is that your car will be completely stripped in order to get a seamless finish. The car is then rebuilt and your wrap looks perfect. The good people who wrap know exactly what they are doing with film, but do they know how to take an expensive car apart and put it back together perfectly so all panels are lined up, all fixings put back in the correct order etc? When you come to remove it, because it is so well fitted you have to have your car stripped and rebuilt again.
If you definitely are going to go through with it then Reforma near Bradford perform quality wrap work.