Used copies of Canon EOS 5D now have very affordable price, however, Canon no longer produce Canon 5D since 2008, so, copies of Canon 5D now are roughly 8-10 years old

Yeah, I find all Canon EOS cameras to be great. I'd go for it.

Although, if you want the most up-to-date quality/specs & you can't afford that, maybe get one on finance?

I'd say go for the Nikon d800s.

I don't like Nikon

For lens, I can purchase a cheap 50mm f/1.8 II or 40mm f/2.8 STM at first, they cost just 50-100 USD if I buy used; and I can upgrade to a used 24-105mm one year later