This goes back to Open Sans, which is what I was using previously.
I really like Source Sans Pro. Unfortunately, the font rendered far too
small relative to other sans-serif fonts, which caused an unpleasent
experience for both slow page loads (e.g. over Tor or slower
connections) and for users with web fonts disabled (e.g. via NoScript).
Further, the font is huge: the WOFF is over 100KiB per font, and I was
using regular and light versions. Open Sans, in contrast, is <20KiB per
font, allowing me to use Regular, Light, and SemiBold and still be about
half the size of the single Source Sans Pro Regular.
As a bonus, users may also already have Open Sans installed on their
system.
I settled with WOFF instead of WOFF2 for browser support.
The site now looks pretty close on fallback, which is good. For
example, I use DejaVu Sans as my default font, and it even has a Light
version that renders correctly.
As with all resources on my site, I host this from my own domain rather
than via Google's servers. That means that the font won't be cached for
users when they first visit the site, but that's okay---privacy is more
important.
I should note that, since I use NoScript, I almost never load web fonts
for other sites. But I still wanted to try to provide a consistent look
across systems for those who do wish to load fonts.
Mike Gerwitz