Namaste all!
First of all sorry as I am posting this message before doing research, so I don't know if the answer is already here somewhere in old threads..

I read mandukya upanishad long ago
In which I found information on Brahman, Pranav (sacred sound-syllable-AUM) and 4 States of mind (waking, dreaming, deep sleep n turiya)

Currently I am reading Taitriya upanishad, I will finish it soon as I have so much free time now.
In this I found some portion of karma kānda n gyan kānda in Veda.. I found 5 koshās (Sheaths) annāmaya kosha, pranmaya kosha. Manomaya kosha, vigyānmaya kosha and ānandmaya kosha.

Now I am confuse that which upanishad I should take for study after completing Taitriya?
So can members please tell me what I will find in other? Can someone give me what content other upanishad can have so I can choose one for me..! So I need some suggestions
Also I am downloading PDF files from internet, I am not sure about its translation so if there is any online source which have better translation so please tell me about that also if one knows..
Pranam..!!