definitely double dicks - wacking off would just be fun. i'd leave the new guy uncut - just to mix it up.
Evolutionary having 5 balls might be better since that means you would produce 150% more sperm than most meaning there is much more ability to spread your genes. The problem though is as humans reproduction is more about quality than quantity and we are also the only species that actively works to tamp down reproduction while still having sex. So 3 more testes might be great if we were coral and just flinging our sperm out into the ocean to fertilize eggs but reproduction for us doesn't work that way.
Two penises obviously. Instead of a threesome with two girls, I could do a fivesome with four. Win win.
I'd pick the two PEE-PEEs. I know all my secks partners have two holes. That is NOT my thing. Thank you, freedom of personal disclosure. For one reason or another, I was under the impression or maybe I had read it somewhere, but one testicle is always the one producing, and the other one is there as a backup. I need to see if that's the case in FACT. Spoiler
I'd rather be rich.....that will get you more poon than having all the penises and balls in the world.