The more you spend the safer they will be.

What you doing with the car ?

Road or track - then some 4 point 3 inch belts will be fine.

Doing any form of competition where you may be likely to hit something and come to a sudden stop and 5 or 6 point belts will stop you submarining under the belts and will save your life.

Take a look at as many as you can and get to learn what sort of mechanism they have and how comfortable the adjusters will be for you imho.