I'd say it's neither because of the way the W is pronounced in German. Though it is indeed close to the English V.

For the German W, the positions of teeth and lips are very similar to the English V (lips slightly apart, the incisors touch the lower lip, though a bit more from the inside, at least that's the way I do them); only a minimal amount of air is pushed through the gaps between lips and teeth, IMHO for a moment none at all. As a consequence the vocal cords stop vibrating for a moment, which I see as the main difference to the English V.

Terrible is open to discussion, aesthetics is an interesting topic. But it is surely distinctive, and distinctive is success because no matter how badly someone spells it, the other person understands and replies yes, this is my number for the payment, or sorry, no.

I don't care if I spell it properly, but once I said Twint in Deutsch speaking Wallis and they understood me, payment made, mission accomplished. For internet shopping, I see TWINT more as a logo than letters from the alphabet trying to form a word.

So, is there something to consider beyond practicality for a payment system? Beauty?