I guess it all depends on who makes the doll, or insert.
The new RDs have a good insert; look and feel.
Ruby13 there is no choice, but the feel is great, and after 4 years, they are durable
The TPE dolls are good once broken in, and I think the look is okay, especially when not spread.
With the insert inside you wouldn't know it unless the legs were spread.
With others the labia are on the insert, and there can be a gap between the labia and the body.
You can't see it in this picture because of the skirt, but the top of the labia sticks out a bit from the body.
Not bad, but not perfect. Some people glue the insert in along the edge so they can remove it if it gets damaged.
Okay Mahtek's Dyanna is a better example. She has a better fit than Paula, but you can still see a line;
But with a little photoshop we can fix that;
For that reason my next doll will have an insert. Even without photoshop the look is good.
Plus all the other benefits of an insert.