I tried one cone of the essential thread marketed for LA. I was very glad when the thread was used up, I was not crazy about it at all and will not reorder. No comparison to King Tut. Essential's cotton thread is ok but some is very linty. I will not order any more thread from Essential threads unless it is YLI silk.
I like Isacord embroidery thread in my LA. I took a class with Karen McTavish in April and she recommends Glide thread from bobbincentral.com. I bought several cones but have not had an opportunity to try it yet. But I did try some of their prewound bobbins and they were great. I will most definitely be ordering more of those.
I have used Superior's Rainbows as well. Beautiful thread but it is very fussy about tension and will break on you until you get the tension set right for it. Highlights is the same way. Both are beautiful threads though and once you get your tension adjusted (very low on both top and bobbin) they quilt beautifully.