I have emphasized one of your criteria.
For me personally, the feel of an instrument can be the deciding factor as to whether it gets used or whether it is a trophy. Never mind if it has the best pick-ups with the best electronic wizardry making signals from strings made of gold tape bound unicorn pubes. The material needn't be wood but thin composites feel creepy. Acrylic is cool. The density of it does something for me. It's a bit heavy though.
I doubt we'll see @Andyjr1515 do one of his ultralight carves on a slab of acrylic however. Andy, if you have any inclinations towards doing that, please let me have first refusal on a build?
What about exotic strings? With piezo, any material can be used to make strings within reason as long as it resonates and is stable. I know there have always been non metallic strings of gut and nylon but recently we've seen neoprene becoming popular on uBasses and the like.
How many different materials are strings made from these days?