Decent GPT script?

I am about to set up a GPT site with a twist, so I need a decent script for that enables a certain level of customization, therefore shiftcode is out of the question. I've done my research online, but I was wondering whether someone with previous experience can share their input on what's best to be used.

Hmm I have been looking for a Wordpress plugin that could complete this, but I haven't found anything decent. If you have any suggestions, whether they are for Wordpress or stand-alone, I would really appreciate it.