I think the world of secure messaging is in an odd-way at the moment. It feels a bit like competing standards at this point[1]. I'm personally still using signal as the metadata shared by Wire is way too much imho.
Even more interestingly the EFF has stopped trying to recommend the best one and instead is encouraging the users to do their own reasearch (even redirects old urls[2])
Signal is great; except there's also tonnes of metadata.
If I'm trying to talk to someone anonymously, having to give them my phone number somewhat defeats that anonymity. Even having it installed is potentially dangerous; it scans your phone book and suggests other signal users (thereby outing you as a user in the first place).
I'll defend Signal here. This is all about your threat model:
My threat model includes:
- kids in my house
- Facebook selling my data to insurance companies
- future employers googling me
- etc
It does not include:
- NSA
- local police (in 2018)
I'll still try to give away as little as possible as while I trust local authorities now I've no reason to be sure I can trust them in 5, 10 or 20 years (see Turkey).
In my case Signal seems reasonable for some things and for now.
Personally I'm also annoying all crypto experts here by using Telegram for some communication and I might even use postcards for other communication (and there might even be communication channels I use but never talk about).
I believe you can deny the request for contacts list access. You can certainly add a Signal contact within the app by typing in their phone number.
I realise this doesn't solve your issue with having to share your phone number with them, or people with your number seeing you use Signal, but if you want anon communication XMPP+OTR+burner accounts is still the way to go, AFAIK.
Even more interestingly the EFF has stopped trying to recommend the best one and instead is encouraging the users to do their own reasearch (even redirects old urls[2])
1. https://xkcd.com/927/
2. https://www.eff.org/secure-messaging-scorecard