I love IT and EIT and have tried a few
Wooly Nylon is the cheapest and easiest to find. However it is quite weak compared to some stuff magicians use.
I’ve never used Mesikas thread except in a Tarantula- it was okay but it was my first IT I used so I couldn’t compare
The best I’ve used is Vectra from Fearson. I think it strikes the perfect balance between strength and invisibility. I’ve got his Virtuoso thread as well - which is even thinner
For EIT I have Legacy Thread - it was referrred to me as the best and I have to agree. It’s strong and very elastic and thin