If you want to go the familiar route then SH4 is your best platform. It has potential way beyond SH3. This is my opinion only: modding SH3 is a waste of time when SH4 is far superior (comparing the two). But if you want all out raw power, flexibility, and a platform that can use advanced features then you have to turn to SH5
They say first impressions last. My first impression of SH4 was that of total crap (because it was SH3 with a little more potential) thus is why I'll never go back to it. My first impression of SH5 was total crap also but peeking under the hood changed that impression in a heartbeat.
I hate the word scripting. It's not really scripting in SH5. It's a way to extend the game. You can make custom dlls and load them into the game via the 'scripting'. If you want to see scripting then look at the script engine I made for SH5 that lets you write your own scripts for the game engine to run.
Wolfstriked I hate working with others. It's just the way I am. I prefer to work alone. It's just much easier that way.