The first to really capitalize on the market I would say. Since, eCash, although being very different from Bitcoin of today was a concept back in the 1980s, which I think was implemented into Digicash? As far as I know, this is the very foundations to what we now call cryptocurrencies, and its interesting to me that the concept was thought of many years ago. I'm not sure of the success of eCash, or Digicash, but I believe Bitcoin is the closest thing we've had that uses similar ish concepts that has garnered the interest of the mainstream media.
I guess part of the reason why eCash failed was because it relied on centralized issuance and therefore was still too tightly coupled to classical banking and the DigiCash corporation itself. Too that end it was more like a hyper-advanced anonymous prepaid payment system than a modern cryptocurrency.
I'd love to think that eCash / DigiCash' failure was mostly due to being too early, but seeing how GNU Taler (ie. a direct descendant of eCash) is also failing to gain traction there seem to be other factors at play as well though.