Looking to start scripting. What's the best platform for development?

I have a few years of workplace Java development experience, and am looking to write a few scripts for personal use/open sourcing.

In your (the reader's) opinion, what is the best platform for developers? I have little to no interest in making money by writing scripts right now. Priorities are mostly a lack of limitations on running private/local scripts. ie: no account/time limit. If premium/VIP/paid membership is required for the latter, that's okay, but I would prefer if it's a one time payment opposed to paying a set amount of money per account one wishes to run.

In terms of scripts, I'm looking to write something that doesn't have a currently working public script. This could be anything, a money making method (anywhere from mediocre to amazing), a f2p quest completer, an NPC killer, a skiller, a minigame completer. Just something useful that isn't currently available. Would love suggestions on this as well.

My only definite 'No' is simba, as I have zero interest in learning a language (Pascal) that has zero real world use.

Thanks for any suggestions.