I've got both on my S21.

I prefer the silicone as the edges are more raised aroudn the screen for protection. The buttons feel better when pressing through the case. Feel in the hand is better too (personal preference as the softer silicone just seems to be nicer to me). And when i hold my phone with one hand i hold my pinky finger under the bottom. The edge of the usb c cutout on the leather case is a tiny bit sharp and isnt as comfortable.

That all beign said, the leather case looks better.

But im keeping the silicone case on my S21 for now.

Edit:

As far as weight goes. They feel basically the same.

And for grip. Just testing them out now, the leather is a bit grippier.

I doubt they will have any cases with a built in screen protector as that hasn’t been a thing since the s7 edge era. And as for the sPen- I know there’s a Samsung official case but that’s all I’ve seen so far.

Try any of these...

Spigen, caseology, ringke, speck, otterbox, uag, iblason, supcase, encased, rhinoshield, survivor, lifeproof.

Cases will cost around 10-50 £/$.