For Liu Kangs wake up he has a few options, it is versatile, but not that strong.
His simplest wakeup is going to be his parry as that can start up really fast and stuns them for a second or to if it lands. This move does not parry low moves however so a sweep will still get you.
The other choice is to try and catch them in a kick but you can be punished if you call it wrong or just whiff.
If you EX it then you have some more potential:
EX Parry is just as good as normal but can be a combo starter if you can land it, a great battle turner, watch out if you use it to early cause then you are left standing there. Or if they sweep it will go through anyway, except now you wasted a bar of meter.
EX Bicycle kick, or Dragon kick both have armor and work very well. Particularly the EX Bicycle kick will armor through their move and deal some considerable damage.
Liu Kang's wake ups are fairly poor, especially if the opponent is going low. If they sweep for example your parry wont activate, kicks will just go over them, all though that is still a better situation, and is to fast to land any normal moves.