You'd have more specific than "every single cloud provider" but in general HAProxy is way more advanced than most other proxies.

Stickiness, rate limiting, gzip compression, configurable logging, caching, Lua scripting, load balancing to domain names, more options for health lifecycle. It even has a control socket to instantly manage the server without restart. HAProxy is actually the inventor the PROXY protocol which a number of other systems have now copied.

The convenience of cloud proxies is no small matter, but on a feature-by-feature basis HAProxy easily dominates.