OB DEFINITELY have a string! They are not as messy as a Diva Cup/Keeper/Instead, IMHO. Plus, I found that when using a cup, my cramps were a LOT worse.
I actually prefer OB, even though I'm old enough to remember the whole TSS fracas that had them off-shelves for a long time. I tend to pinch myself with plastic applicators, and cardboard is annoying. Granted, I ALSO have REALLY short nails--something to bear in mind if you go applicator-less. I think the reason I prefer to be applicator-less is because of the waste and because if I'm not carrying a purse, OB fit better in my jeans pocket. Hell, even when I have used U by Kotex, I take it OUT of the applicator and treat it as IF it were an OB (again, the pinching. Don't judge!) I'm not personally skeeved out my ANY of my bodily fluids, but I do understand why some folks are--it's cuz it's not JUST blood, it's ALSO your uterine lining....and I'd be mortally skeeved out by placenta, so no trippin', IMHO. Everyone has their thing.
The Kotex reaction is BAD, though. I REALLY don't like that they said, "It's a mold not dissimilar to a bread mold" or however they phrased it, cuz you know what it is that molds in bread? YEAST
I think I've said QUITE enough.