I have two acavallos which have been great, however the black on has faded in the sun. They are perfect for a slightly thicker half pad without being overly filled. For thin ones my favorite is the equifit half pad.
I like ogilvy, I've used their half pad to help with saddle fit until I could get a saddle fitter out for my horse, but it is not a long term solution for saddle fit. If you have a properly fitted saddle, and want some shock absorption (either for you or your horse) it would be great - based on my experience (and of those around me).
I currently use a thinline half pad (got it from my saddle fitter) and we've been using it and adjusting the shims in it so my horse could fill out into the saddle, which he has. It's been great to have and I'm still using it.
I don't have any experience with Ecogold, or personally know anyone who does, but I've read/heard good things about it, but don't really know enough about it to form my own opinion.
I think ogilvys are great. My only criticism for them is that they are very thick, and can sometimes disrupt saddle fit.
I love supracor hunter junper cool grip half pad. It's the only half pad I know of that actually helps saddle fit, rather than just putting extra padding and memory foam between the saddle and the horse.