Which one do you like better?
Or is their a netter piston gun?
maybe mcx?

I have both...actually both converted MR556 to 416 and SL8 to G36...but I have also enjoyed both rifles in their previous and current forms.   Both are great rifles with respect for what they do whether it be mid range accuracy in their original forms or CQB in their current forms.  The one thing about the SL8/G36 that it is strikingly advantageous in its weight.  It is surprisingly light and way more nimble compared to the MR556, but that is to be expected considering the SL8 is primarily made of composite carbon fiber mix.  Both systems are great...run cool and run clean.  I’d say the G36 is a little more friendly on blow back when suppressed and is not quite as violent with the bolt action when compared to that of the over-gassed MR556.

Who did your bolt work for the g36?
Which mag well did you go with?
You know of any sl8 for sale?

I have a genuine German G36 bolt.

I am using the original G36 magwell that takes double stack G36 mags.

I do not know if any SL8s for sale.

I dont have one but throwing this out there:
https://www.tommybuilttactical.com/t36-receiver

Just came across that last night.

I have a MR556. Expensive and heavy, yes. But worth every penny it cost.