I recommend everyone interested in the two try both. I personally prefer Unreal Engine, but everyone is different.
Unreal Engine is also moving quite quickly, adding new features, marketplace content, improving the UI, etc.
Unreal Engine's built in networking systems are suitable for 64 players, maybe 128 tops. It's replaceable, but I wouldn't recommend delving into that.
I will say this though, if you have 1 C++ programmer with UE4, they can create functionality not builtin to the engine and expose it via Blueprint (the visual scripting language) for non-programmers to use. Blueprint is a fantastic and very easy to use tool. Take a look at the forums to see the incredible things people have built with ZERO programming knowledge.
And talking about Blueprint code is done through screenshots https://forums.unrealengine.com/showthread.php?60637-Unable-... I guess there is still no auto generated text representation you could copy paste.
https://mono-ue.github.io/about.html
If you want to code in C# it is the primary language for Unity, and a commercial third party unsupported add on for UE4.