Tbh they’re both good but it’s just preference. The s20 looks more warm and saturated while the OnePlus looks way more natural with vivid colors and better exposure. I edit on photoshop a lot since I like to take pictures and it would be a pain editing the s20s picture because of the weird color.
I mean, the S20 looks warmer. And is slightlyyy better exposed. But spend 1 minute in light room tweaking 2 knobs and they’ll be indistinguishable. Not worth the extra $300 if you ask me.