Biotin shampoo and conditioner vs keratin shampoo and conditioner. which would be more effective in growth, repair and/or nourishment?

Neither.: Shampoos and conditioners have little or no effect on hair "growth, repair and nourishment". Oral biotin (5000 units/day) has been shown to have some beneficial effect - but in general, eat a healthy diet and minimize drugs & alcohol, and your hair will look great and stay healthy.

Hair repair: Keratin shampoo/conditioner coats the hair shaft with Keratin (protein), protecting the hair shaft. Biotin shampoo /conditioner wouldn't be effective , because the hair shaft can't use it. Biotin is a vitamin that helps in the maintaining strong hair and nails, but it must be taken orally to be effective.

Both: While keratin is for nourishing the cuticle of the hair strand biotin is only absorbed internally not topically...so for best results use a product or products with both, keratin shampoo and biotin orally.