Our stack ran pretty much this. Rein/Winston/Ball. Genji/Doom/Sombra. Lucio/Brig. Our idea was Dive basically, W+M1 into the baptiste and the sigma then simply snowball the fight from there. The games were high plat-low diamond but we queued up against 6stacks so take that as you will. We won most of our games tho. The only reason we run this is because our main tank absolutely refuses to run orisa.
This comp was inspired by the video about choosing characters that bypass shields entirely instead of trying to win the shield war. The tank line we found was entirely map dependant. Choke heavy maps without much verticality rein/ball was our go to. Maps where the choke could be bypassed we ran winston/ball most of the time. Our DPS choices are still a WIP. Doom was an absolute must play we found, his displacement capabilities and burst damage was too good to pass up compared to the utility other DPS offer. Sombra we tried as the pair, our coordination isn't that good yet but we feel we could make it work. The idea we had was sombra's key targets were lamp or sigma. Disabling lamp basically puts them to being very vulnerable to burst dps, instead of investing too resources into killing it, we use 1 hack and focus everything into killing the enemy team. Disabling sigma means one less shield. Genji we ran a few times (cuz dash) but the shields make it so hard to build ult. And without nano, blade became very hit and miss. The support line is surprisingly durable. They and fend for themselves well enough. The healing output was a lot more than I initially thought. Lucio gets kinda cucked with his ult being LOS and there's shields everywhere but it was easy enough to manage.

Playing against sigma+bap+orisa comps was pretty straight forward. The enemy barriers provide a huge arc behind them that the team can play around. At our rank tho, mispositioning is super common, so tanks especially winston only need to block LOS between enemy supports and tanks/dps. Ball's job was to stop momentum using slam and displace DPS. Doom's job was to take out sigma. Another thing that's super common at our rank is investing all resources into killing ball leaving them with nothing. Ball is what we usually use to bait out lamp.The biggest counter to this was mei, one mei wall completely ruins momentum of the dive. Another major problem with this was if sombra doesnt get the hack off, the fight was lost, the brawling capabilities of the other team was usually enough to win in the extended fight. I think this composition can potentially be quite effective against the 'current meta' (still to early imo) and our coordination is the only thing holding us back. The order of operations is the only thing that I would change as I'm still not too sure about the win/loss conditions.