My guess for why they chose the letter g is that gnu can be phonetically the same as just nu, but keeps people from interpreting the name of the project as a dumb spelling of “new”.

In my opinion, both services seem usable for free, anonymous, web based email, but the proton mail CEO made some alarming political comments in support of conservatives and Donald trump. I would prefer that a company stay apolitical when a major appeal of their product is supposedly privacy.

It’s wise to question motives but in this case I get the feeling they’re the good guys.