If camera is your top priority, the Pixel 8 probably wins. Its computational photography is generally considered better for everyday shots, especially of people and in tricky lighting. The iPhone 15 is great, but its strengths are more in video and a 'cleaner' more natural look that some find less immediately impressive. For longevity, both should be fine for 4 years, but Apple tends to support devices with software updates for longer than Google, so iPhone has a slight edge there. The performance difference for your usage (social media, YouTube) will be negligible.