Redis seems better because it doesn't act as a proxy. And for WordPress Redis will make your website faster without making the content static.
Varnish doesn't support SSL natively, and if you are using Cloudflare, it already cache your static assets, so that's another reason to prefer Redis.
Varnish is excellent for delivering static content. If you require SSL, with xVarnish for example, it is extremely easy and fully supports SSL over Hitch. Varnish + PHP opcache for easy setup with support for PHP caching and static content.
I have probably read some of the same articles that you have. There seems to be a lot of comparisons between these two with any clear answer for which one is best and why. It's also hard for some of us new to this since a lot of info is a little too technical. I have been giving myself a headache looking for some clear answers on this. Time for the tylenol.