Heres a little read for you.
Everybody will have a different opinion on whats better, for what reason etc.
From what I researched, TRD's are tighter than the Kaaz's, but becuase of this are a little more unpredictable than them as well. I didnt research the cusco's much at all.
You can pick up a Kaaz 2way for under $1000 from RMS in melbourne.
TRD LSD's you can purchase rebuild kits for about $600.
But I doubt you'll need to rebuild your LSD anytime soon if you purchase a new one, and change the oil when needed.
I bought A kaaz 2way, but start searching, filter through all the crap, and goodluck making up your mind!