Right now I would agree with you one it comes to choose the coin that works best as "digital gold", or gold 2.0 (whatever the name they call it now). It's gaining acceptance among Wall Street investors, with the release of futures market, and it should soon get ETF approval, so it's all set for bitcoin to become a new asset class. Because of it's characteristics, it definitely resembles a lot with gold, but it enhances it further, since it's transactions, mining and storing, are a lot more secure and efficient than using gold.
As for Dash as a payment method it's hard to say. The currency status, or new payment method status, for crypto hasn't been decided yet. Mos cryptos are still to volatile, so even with low fees, it will be hard to use them as a payment method right now. Also, let's not forget that is the lightning network works well, Bitcoin could also enter that race again, so nothing is decided yet.