definately PU is harder to crack to due its flexibility, however, onces it does, thats the end of it. You cant fix it back. Price wise, PU is way more expensive as well, not only pricing on the b/kit itself, but paint as well, because PU material doesnt hold paints well.

For me i would always prefer fibre, not for the price, but for the customizations. There are different grade for fibres as well, not all fibres are as fragile as what ppl think. Then again, for lowered cars, its better to use PU side skirts, since theres not much to customise for side skirt eitherways.