We use Forge because they support our non-big-3 Cloud provider and because they take the headaches out of provision systems. Overall, it's been great.
The thing I love/hate about Forge is that it makes some stuff JUST easy enough to not have to build yourself, but also makes it just frustrating enough for the customizations/tweaks we've built up over the years.
More recently, we started using the API to script various setups and configurations. It took processes that used to take several hours and made them minutes. This means we avoid having to figure out and manage things likes what the default nginx config is across servers. But then, there is SOME stuff like PHP ini files that you can't modify via the API. So we end up running an amalgamation of API commands with some "command scripts" that do the one-off things.
All things considered, I wish there was an Ansible migration path off of Forge. There are so many little things we've had to do that results in our needing to create and run one-off scripts but Forge has just the little bit of edge that migrating off is "more trouble than it's worth".
I just with they could fix the team dynamics. e.g. I want to be able to have a library of scripts (forge: recipes) my team can run—but since I'm the account owner, only I can run them!
One of the big things that Forge did for us a long time was handling of deployments. The ability to just have it respond to a commit: download the code, do the build and then restart FPM, was great.
We don't use that anymore, but we use it for provisioning and maintenance of systems... it's not GREAT at that, but it is still super nice to be able to say "stand up a MySQL server" and then it's just up and ready to go in a few minutes without having to deal with Ansible and Akamai...