Katanaka snipers are a definite. I always run at least one with shen long and sensei yu.
I am quite partial to lone swordsman, but Izamu is great as well... or both
I second Shadow Effigy and 10T brothers, though tengu are also out and are solid. I'd recommend the effigy and then pick one of the other two for schemes.
I also really like Kang from Mei Fang's box.
Oiran. The +1 willpower aura from Oiran is just so clutch in many situations, the upgrade to make them fast and focused costs 0ss and they are cheap.
Shadow Emmissary has a fantastic upgrade with Shen Long. Also because you will be running Yu with at least one upgrade and another beater with at least one upgrade (even if its just the oiran one for free), he can push and hand out fast like a boss. He's deceptively good in combat too with his repeat attack trigger. And it's got range 7 with no shooting icon.
Ten Thunder archers are solid, especially if Yu has blot the sky. Shen gives them 0 action to focus, Yu gives them +1 to shooting when focusing if within 3", which works fine because he'll probably be too busy supporting to move to much after turn one. They have read the wind which means the 0 action to focus is for +2. I tend to focus at the end of their activation so blot the sky's ability gets the double focus at end of turn, but obviously they have to not be dead
My typical 50ss list with shen long looks like this:
Shen Long (+2 soulstones) - wandering river style, words on the wind - 4
Sensei Yu - Promising Disciple - 11
Lone Swordsman - Recalled Training - 9
Katanka Sniper x1 - 7
Peasant x1 - 2
Shadow Emmissary - Conflux of Dawn - 10
Oiran - 5
Turn one: Pop new peasant with witness a miracle. Emissary moves up, pushes Yu and fasts him. Shen activates and moves up, focuses, pushes, hands out fast. Yu doesn't move, just focuses, pushes and hands out fast. Sniper normally gets two shots off. And the lone swordsman ends up ready to charge into something big and tasty with fast and recalled training.
Or something like that