Your choice on what is visually pleasing. They will twine around themselves if not given some support.
They are notorious re-seeders so you should get plenty next year.

Hi,

I have been using jute twine for my morning glories to climb. I attach open paper clips in the openings in the soffit of my shed and string the twine up & down from the ground. They cover the twine in no time and clean up in the fall is easy. Just cut the twine and discard the whole mess. Saving seeds of course if you wish.

Pam

I use lattice. They have no problem climbing over. It is a twiner. I get volunteers all over the area in next spring.
Would you like to see my gorgeous climber?

Lakshmi