If you're a professional then you can ask yourself the question.

- All 24x36 sensor DSLR's on the market are in the professional segment. They are big and expensive and tend to require lenses that are big and expensive. They produce the utmost image quality unless you decide to go to medium format. They give you the maximum performance in terms of images/second, autofocus accuracy, etc.
- There are also professional bodies with smaller sensor sizes which have almost as good performance at much lower cost with a smaller, lighter body and accessories

If you're an amateur it's easy - smaller sensor sizes rule with a vast variety of systems.

If you're somewhere between the two, like many people on this forum - it's up to you to decide. I would say go for the smaller sensor unless you have the knowledge and need for professional material