When I was looking to upgrade from lvl 3 steel, I noticed most companies 3+ was more expensive than lvl4. Which caused me to just buy lvl4's.

Some makers make 3+ in steel still. Which is thinner by a lot when wearing them.  And once you go lvl4, it's pretty much ceramic type, which is thicker.  But with ceramics, you can also spend  more and get lighter. Like instead of 8lbs lvl 4's you can get 4lbs lvl4s. And the weight doesn't seem like a lot, but after being in the sun for 4-5 hours, it does make a huge difference.

The above are rifle rated.

I didn't watch the YT vid, but soft armor would be 3A or less and not rifle rated.  As the title states, "which soft armor panel is the best" is why I made the assumption.  Except Safelite which has 1  up to 50 cal rated.  And there is a vid of it taking a 50 cal hit on YT.  IIRC the channel is Edwin Sarcasian or something. He calls his uncle "jabrone" all the time.  Then there's soft armor Dragon Skin by Pinnacle, but they went out of business in like 2006 after they lost the Army trials. So I don't think you would be able to find Dragon Skin anymore.