Hmm. Tough one. Some mobile apps require you to sign up via the browser. I think, for now, I'm okay with that being the case here. The more STEEM the Steemit account can distribute to others, the better off the whole platform will be. There's also the concern about people creating a lot of accounts through your signup flow without having to authenticate with Facebook/Reddit.

So I guess my answer would be:

0.. None of the above. Go to Steemit.com to create an account.