Bitcoin Diamond is a hard fork of Bitcoin that promises to deliver on privacy, an issue that has been elusive with Bitcoin itself. The developers have discovered how to encrypt the transaction amounts and balances of all BCD users.
This coin promises to offer fast transactions, with 8MB block size limit. This means that it has copied some code from Bitcoin Cash In order to deliver on this. While this is probably one of the best offers, the discussion concerning on-chain scaling may not be over yet. But this can help reduce network congestion that has existed up to now. Even with this, BCD does not seem to have any future plans to increase the block capacity.
The worrying thing about BCD is their aspiration to issue 210 million BCD. This is x10 of Bitcoin supply, confirming that this is not a direct hard fork. According to their website, BCD uses the X13 mining algorithm, which should give GPU miners something to do but also supports SegWit.