Not even in the same ballpark. Humans actually need trace amounts of copper. Regulations for safe copper levels are almost 100 times that of lead.

All pipe materials are poison if enough is ingested, lead is however is toxic in extremely low amounts, while copper is actually needed in low amounts. You think PVC is better?

Lead is the worst by a mile, but If you expect to have water in the very low or very high PH rank, or water with a lot of chemical activity or too hot, copper is not totally safe either.

We, mammals, are relatively well protected to deal with it, but the real problem here is in the long term exposure. Can produce several forms of inner bleeding in the gut, and harm permanently the liver and kidneys. There is a lot of copper messing around for some reason in Alzheimer's patients also.

Moreover copper is particularly toxic for all aquatic life and invertebrates also causing an acute poisoning. I would not use that water in an aquarium for example. I had seen the stuff in action and is devastating for fishes.

Fish tanks require copper to maintain proper levels of nitrifying bacteria, the first two nitrifying stages require copper to convert stuff to the "safe" nitrogen that requires flushing to remove (unless you have real plants in the aquarium, then you rarely need water changes) - furthermore, copper is used to cure several fish diseases[0], so it it's impossible to be as bad as you claim.

[0]https://smile.amazon.com/Seachem-67105650-Cupramine-Copper-1... for example

This is a myth. Fish tanks definitely don't require a surplus of copper. Not unless they are hospital tanks. I have experience using copper to cure fish diseases and cant guarantee you that is a notoriously treacherous stuff to work with it

What is, what I'll call from my layman perspective, the leeching factor of copper vs lead pipes though? As in, how much copper vs lead ends up in the water being transported?

The choice is not between copper or lead, is between copper or pvc, steel... or even ceramics. Lead is unsuitable for drinking water.

Stainless steel would be better, excluding exotic materials. You cant really get iron poisoning.

Turns out you can, though probably not from water pipes (if I skim the article correctly, it'll need to be ferrous iron).

https://en.wikipedia.org/wiki/Iron_poisoning