..., I do agree that Pelikan Black is a heck of a value.
It's a good enough black ink, fairly water resistant, but it can write dry, IME. I have quite a bit of Pelikan 4001 Brilliant Black ink.
My main black ink is Noodler's Black. For economy's sake I mix it with the above named Pelikan Black and some black ink that's watery. I am in the process of finishing up the Visconti Black for that mixture and will go on to some other watery ink soon.
I have to say that I do not agree with the OP's assessment of the cheapest black ink being the best. In some cases the same ink is cheap or pricey depending on where you are. Also, if you want archival and/or totally waterproof or bulletproof ink that makes the choice more complicated.
I once got a bunch of black ink that turned out to be carbon black ink, with carbon particles in it. I hadn't known it was that when I bought it. I never put it in a fountain pen. While I was weighing the risks of such particle-based ink in my pens I opened a bottle up, and the smell of burning rubber tires that came out of that bottle convinced me that it was not an ink I would want to use. I sent it back. This stuff was amazingly cheap, probably the cheapest black ink I have ever bought, so it pained me to have to reject it.
In the end, of course, it's all mostly subjective and up to what we personally prefer.
I'll throw in a gratuitous shot here and say that IMO Quink Black is only a gray ink.