Single vs Dual Channel RAM. What's the general consensus? The pros and cons? (2x8gb vs 1x16gb)

I've looked up a lot of videos already and have conflicting information.

1. Do you get better performance for Single Channel RAM or Dual Channel Ram?
2. Is it different for DDR4 vs DDR5?
3. Is there a general cost difference?

I'd like to know what Reddit thinks. Thank you in advance for your answers!