JM Custom Kydex. A lot of thought and work went into them and it shows. Their AIWB Wing Claw setup is second to none IMO...and he just came out with a new AIWB Wing Claw 2.0, which I'll probably be ordering shortly, after my last order clears.
Yes, the lead time is a little long, but it's worth it. And, he has quick order/ship products, mostly all Glocks, so if you have a 19, you should be able to get one pretty quickly.
And yes I see a huge difference with and without the wing...with the wing, it's hidden a lot better IMO; it conceals under a t-shirt. Without the wing, it mostly conceals but you can tell it's there if you're wearing a plain white t-shirt for example...
Edited to add - the wing claw doesn't push into you - it pushes against your belt, pushing the butt of the gun into you a little more, for way better concealment. You honestly won't notice it, unless you're even fatter than I am...and I'm pushing 270