I don't think we've ever formally surveyed such things, but from watching what pops up frequently I know we have a fair amount of "DIY" games/engines (frequently using C++, sometimes C#, or occasionally more exotic languages), plenty of Unity and Unreal users, some Godot and Urho3d users, and a few using tools like GameMaker and Construct.  Some of the AAA devs use proprietary engines at their respective studios.  SFML, SDL and (to a lesser extent) Allegro all used to be very popular but seem to be less commonly mentioned more recently.  MonoGame gets a bit of usage too but seems to be a less frequent choice.

I'll share a secret with you OP...

Generally, the smart people use the best tool for the job, they look at the requirements of their game and then look at what each tool will offer, generally for example people might choose Unity for a web game or UE4 for a first person shooter, but there is no hard and fast rule.

The not so smart people use what others tell them to use with no research. This isn't a dig at you, or anyone in particular, just an observation I've noticed through many years of lurking here and elsewhere.

I hope this helps you as similar advice once helped me!

You can't go far without hearing the name "Unity". Should you use it?  That depends on the nature of your curiosity...