For Aytal Kursi, I have heard following ways of recitation ....

Question
Salamalaikum
For Aytal Kursi, I have heard following way of recitation
1)    Allahu la ilaha illa Huwal Hayyul Qayyoom
2)    Allahu la ilaha illa Huwa, AlHayyul Qayyoom
3)    Allahu la ilaha illa Hu AlHayyul Qayyoom.
Whether all the above is correct and how.
Jazakallah Khair

Answer
Wa alaikum assalaam wa rahmatlullahi wa barakatuh,
We can only judge from what is written, but it seems like one and three are correct as long as the reader is stopping on the word in number three because we stop with a sukoon on the last letter of a word. 
If, as written, number two is read with the word   with a vowel without connecting directly to the laam on the next word , then it is not correct.  The hamzah wasl at the beginning of the word should not be pronounced when continuing, only when starting with this word. 

And Allah knows best.  Since we cannot hear the recitation, we can only judge on what we have extracted from the writing with English letters.
Wa iyyaakum.