I mostly use Winston as a harasser to try to knock the other team off their focus, by leaping around into their backfield, zapping who I can (which as often as not doesn't kill anybody), dropping a barrier when they start to shoot at me, and hopefully by then the 5 second cooldown has elapsed on my jump so that I can leap away. Then ALSO hopefully, my team has started advancing and shooting them in the back, which also doesn't happen as often as not [emoji14]
But there has been the odd match where we were completely bottled up in our spawn (like the first Volskaya chokepoint with the truck and whatnot), and I managed to jump over/around their defenses to go get on the capture point, which leads them to run back to it, and let the rest of the team out.
But more and more often, my most effective attack character continues to be good ol' vanilla Soldier 76.
I wish I had thought to put up the entirety of that defense match in egypt where we went 5 S76's and one Symmetra (because Dei hates fun). That thing was an amazing stompfest, the other team couldn't get beyond the first chokepoint either.