Saifa & Seiyunchin
Saifa is the shortest kata of Goju Ryu but it is not easy at all.  The students start practicing this kata when they already know all the basic stances, blocks, punches and kicks to be able to jump to a different category of kata techniques.  Saifa demands more control over every single movement, stances, punches, kicks and balance at the same time coordination.  Once the student starts working this kata he will feel the change of the karate techniques that demands much more work, attention and understanding of him and the kata.
This is an advanced kata from Goju Ryu the techniques involved are more complex .
Geki Sai Dai Ichi & Geki Sai Dai Ni
This are the first kata that every white belt needs to learn.  This kata have all basic defences and attacks needed to defend and defeat an agresive attack. 
This kata demands all the spirit to execute it.  Mastering this kata is a very hard effort but once you learn it you will keep practicing for ever to look for a good execusion.
These Kata  are performed by the Goju Kai senseis from Japan