Satoshi Nakamoto always referred to it as such:
block chain
However, I see the term "blockchain" used a lot anyways. Do you think we should use Satoshi's terminology to prevent confusion with Blockchain.info, who will usually just refer to themselves as Blockchain? Or am I worried about nothing?

I voted Blockchain and it seems I hit the majority. I think blockchain has gone a long way since its creation and now it should be called Blockchain, just like the Internet.

Or we could call BTC blockchain a Blockchain and all other altcoin blockchains just blockchains - not start with a capital letter like the original BTC Blockchain that started it all