Just about every manufacturer offers something in the category but when you say "SBR" upper, exactly what length are you looking for? 300BLK uppers come in a wide range of lengths. You can find "SBR length" BLK uppers as short as 5.5" and as long as 12.5" and just about every length in between.
I have (2) BLK uppers, a 7" DD PDW upper and a 9" BCM. Between the 2 I prefer the BCM upper because I feel like that extra 2" makes a noticeable positive difference (rail space, sound level suppressed, velocity) and I'm not using it as a backpack gun so I don't need it to be super compact.
So I'd suggest you first step should be to define your needs/wants in order to determine what length upper you want and that will help narrow your search.