I would buy the Ruby Comp Disc that is $400 more than you planned to spend. Comparing the bike Muirenn linked to and a Ruby Comp Disc that is $1950, the components on the more expensive bike are two levels better and in my opinion are worth the investment. And it's comfortable for you, which is very important.
I can't speak to disc brakes vs rim brakes, since I've only used the latter. There is a thread or two discussing the advantages of disc brakes somewhere on this forum, should be something you can find by searching.
- Gray 2010 carbon WSD road bike, Rivet Independence saddle
- Red hardtail 26" aluminum mountain bike, Bontrager Evoke WSD saddle
- Royal blue 2018 aluminum gravel bike, Rivet Pearl saddle
Gone but not forgotten:
- Silver 2003 aluminum road bike
- Two awesome worn out Juliana saddles