Introduction
In most cases, your best super pick is SA1. Gives a lot of meter, and the super itself does fantastic damage.
SA2 is mostly outclassed by SA1, but has uses against Ryu, as you can escape/punish some denjin setups with it.
SA3 for the most part isn't worth it unless you can pull off the infinite meter glitch.
Moves List
Normal Moves
Special Moves
Super Moves
SA1 (Raishin Mahha Ken): QCFx2 + Punch
Unlike in 3rd Strike, this super is pretty good. It has a long bar with 2 stocks, which is great for EX Mantis Slashes. Thanks to Yang's light to medium TCs, it has relatively easy confirms which do a ton of damage. However, it is a bit lacking in some utility that SA2 has. It's range isn't great, so you won't be able to use it as a punish in many situations. On top of that, on anti-air or from some confirms like stand MK and Byakko Soushouda, it won't fully connect and miss out on a lot of damage. Still, if you prefer more explosive damage and having more EX moves to throw out, SA1 is a good choice.