Purely your choice....
Seed pros and cons....seed is cheaper and easier to put down. Its also available almost anywhere...even argos or supermarkets sell it these days. However, the seed bed needs much more preperation and it may take weeks, if not a few months for the seed to come up, and then it may need over seeding if the germination has been sporadic. You also cant walk on seed for a few months.
Turf pros and cons.....can be expensive, heavy to move and awkward to lay. Only usually available from turf nurseries. Needs plenty of watering to stop shrinkage. But, you get an instant lawn and boy does it look good when it's down. You don't have to be so thorough when doing preparation and you can walk on it after a short time.
For me....turf all the way.