I'm in the market for a upper for a lower I'm in the process of SBRing. This is going to be my first rifle that isn't 16'

It seems everyone is favoring the 11.5 over the 10.5. It makes sence why after reading BCMs write up.

I can't seem to find anyone other than BCM and KAC making 11.5 uppers. Is 11.5 inch barrels a newer thing? Is it just good marketing? Forgive my ignorance to the SBR thing.
I know I can put something together, I'd rather just have something complete this time.

For what it's worth the uppers I've been looking at are not all 11.5.
Uppers I've been looking at

BCM 11.5 Mlok
LMT MRP Mlok 10.5
LMT Mk18 + MK8 rail

Am I looking is the right direction?