Hello. I have worked with both of them. However, this is my personal opinion. You can search on google for better results:
1. For little games like game jams or indie games unity has better efficiency.
2. For mobile games unity is better.
3. For 2d games, unity has better tools.
4. For big projects like AAA games, unreal has better performance.
In unity, you can create awesome effects with "Unity Visual Effects Graph". You have to practice a lot with it. First-time effects aren't very good!
You can learn unity with brackeys youtube channel.
This is my game made with unity with WebGL and windows output. please try it! https://itch.io/jam/brackeys-8/rate/1681109