Thongs are mostly comfortable--especially the brazilain cut (has a little more fabric so does not pull 'up' your *** so much, but exposes the cheeks)
Gstrings--I feel are uncomfortable for more than a few hours. I rarely wear G strings unless I know they are not staying on..i am not trying to sound sexy saying that--it is just truth, they are not comfortable.
mesh thongs are best for panty line--you don't feel them at all and cant see them.