Go ahead and read the material for DGB and see all the items it offers over Bitcoin. My biggest selling point is how fast the transactions are. Way faster than BTC. And with Digusign, it makes it marketable to businesses.
So the things that make DGB attractive to me are the fact that it's multi-algorithm mining and it's fast for transactions. I think the key is the speed of transactions, why BTC continues to shine is all market momentum and a desire to have a "standard", but at some point that could change.
DGB is a good coin and it has all the needed pieces to be a top coin.... now it just needs stability and significant market penetration.