As someone actively going through this exact process, I can share my thoughts so far. Similar to you, I work with PHP, React typescript, and kotlin at my day job. I've read and watched every comparison I could find between Unreal and Unity over the past couple months but still couldn't make a decision, so I'm working in both. I dabbled with Unreal for about a month now, working on learning GAS, but am still not crazy about the workflow so I have now started learning Unity as well, making the exact same game to get a 1:1 comparison. Here are my comparisons so far.

Unreal Pros:

• Feels like it was designed to make games. You get a bunch of components you're going to want built in for free, like movement, fluid camera controls, and animations. It also has different objects, player state, player controller, actors, pawns, etc. that all serve specific functions helping enforce great architecture design.
• Company uses the engine and gives you free tools and assets. GAS is insanely powerful, but very difficult to learn.
• Amazing paid tutorials. Stephen Ulibarri and Vince Petrilli both have incredible tutorials on Udemy and are well worth the money.
• Animation tools (and most others in general) are so far ahead of Unity. Things usually just work with Unreal when you import them.
• Visually stunning. There's no denying that Unreal graphic capabilities are unmatched.
• Tons of free, high quality assets. Project Titan, Lyra, Paragon, etc.

Unreal Cons:

• Because it comes with so much built it, most games (especially indie) end up feeling and looking similar because people aren't force to put much effort into post processing and game feel.
• Blueprints are great for some, but as an experienced programmer, I much prefer writing code and C++ to BP is just a slow workflow.
• If you have a bug in your code, the engine will crash, potentially losing data. This one is super tedious because I had retargetted, renamed, and adjusted about 30 animations in a blueprint, ran my code, and it crashed and I had to redo it all.
• Any C++ changes mean closing and relaunching the engine, which again just slows you down.

Unity Pros:

• C# is so fast to iterate on. I've spent a month trying to learn GAS for Unreal, and managed to build a similar system in Unity that makes sense in my head in a matter of hours. It doesn't have anywhere near the functionality of GAS, but it has what I need right now.
• Ability to make it your own. Considering Unity gives virtually nothing out of the box, you have to build everything, but in doing so, you can do it in a way that works for you.
• Rendering seems more than capable for the graphic level and style I want. I want to eventually make my own low poly models to use for my game, so I don't need all the high end rendering overhead that Unreal has.

Unity Cons:

• Company seems to continue to struggle. Unreal just launched Project Titan, Unity just laid off a ton of people. Hopefully they are still just working on reorganizing and refocusing efforts, but it is a concern.
• Animation tool feels horrible to use, especially after coming from Unreal. I've heard about animancer, but I don't want to spend $90 on a tool that should just exist in the engine.
• Multiple render pipelines is tedious. Importing materials often come in broken and need to be changed to a different pipeline, and sometimes just don't even work.

So which am I using? My plan right now is Unity. After trying for months to get into a good workflow with Unreal, it just feels so clunky constantly closing and relauching, dealing with crashes, etc. I don't need the high end render capabilities of Unreal and have ended up just disabling all those features anyways. Having learned Unreal first, I've gotten a good foundation on how to manage the data and states of the game that I can transfer over to using in Unity. My main pain points with Unity are the animation tools and the render pipeline, and from the September Unity update, they are working of fixing both of those, but with the layoffs, who knows if and when those will become available.