For the average developer, Unity still has the best balance between simplicity and resources (learning, assets, community) but looking forward, if I was starting out today, I'd go with Godot for indy games. When to go with Unreal is a whole different matter, but for the beginning, Unity is losing its luster.
Unreal has been the best choice for high-end 3D games, and will likely remain so.
For every other type of game, I would at least check out Godot 4 once it's had a stable 4.0 release. It's easy to learn, supports .NET, and it's actually not hard at all to modify and extend if you know C++. It even compiles from scratch relatively quickly.
Unity's biggest advantage is the Asset Store. If you want a bunch of third-party plugins to make your life easier, Godot has a long way to go.
I agree that Unity has a head start, but we're betting on Godot catching up, especially for indie developers. We're doing our part by helping to plug some of the holes in the Godot ecosystem by releasing assets, game templates, and plugins.
Unless you are a massive AAA shop with oodles of time and resources to devote to a bespoke engine, if you are writing a game you want to use either Unreal or Unity. It instantly gets you onto every PC, mobile, and major console, and there are lots of programmers and designers out there with skills specifically in those engines.
Maybe if things get really bad, Godot or something will overtake Unity someday, but that day is not today.
Console industry is overwhelmingly shifting to Unreal, but as far as I know Unreal is still lousier than Unity for mobile dev, and Unity remains the preference for that platform.
Yes, but nobody actually develops games for Mac and Linux. They target Windows and then build against Winelib if they're countenancing a SteamOS release.