First, there is no real reason to have a separate neck cream - your products can be the same for face & neck. The exception to this is when you know that the skin on your neck is more reactive than your face, then using a product with less actives for your neck would make sense.
Overall, you need 2 types of products for your neck (or your face & neck):
- a day-time moisturizer with sunscreen (a few good options: https://whatsinmyjar.com/product/paulas-choice-clear-ultra-light-daily-hydrating-fluid-spf-30; https://whatsinmyjar.com/product/la-roche-posay-toleriane-double-repair-face-moisturizer-uv-spf-30; https://whatsinmyjar.com/product/avene-avene-hydrating-cream-spf30; https://whatsinmyjar.com/product/paulas-choice-resist-anti-aging-youth-extending-daily-hydrating-fluid-broad-spectrum-spf-50-full-size)
- a night time moisturizer, ideally with anti-aging ingredients like retinoids (if your neck skin can tolerate it), niacinamide, peptides. A few options: https://whatsinmyjar.com/product/avene-avene-ystheal-anti-wrinkle-cream; https://whatsinmyjar.com/product/paulas-choice-resist-anti-aging-intensive-repair-cream; https://whatsinmyjar.com/product/olay-regenerist-whip-face-moisturizer)