I need to start using reverse proxy and such things. Have you decided upon that instead of Nginx Proxy Manager or Caddy? Or are you using HAProxy to solve other challenges?

I use it for a few other things than reverse proxying. HAProxy seemed like a light weight solution to what I was looking for: parse an incoming request and hand it to something else as fast as possible, and doesn't do any web hosting itself.

Are you only using it for reverse proxying/rate limiting?

I primarily use it to terminate SSL, route based on hostname (subdomain), and cache.

I use mine to also terminate TLS and proxy mosquitto (mqtt) traffic. mosquitto's TLS configuration is a pain and it's so much easier to have it all in one place.

I do the same for my personal machine. It's acting as the router/gateway in front of several Docker containers (both HTTP and also other protocols, such as SMTP or IRC).

Disclosure: I'm a community contributor to HAProxy.