It's completely subjective. I use this and it works for me. I am not claiming it to be the best, but I like it. http://www.basspro.com/T-R-U-Ball-reg-T-Handle-Thumb-Release/product/24196/-541776
IMO you can't go wrong with either Scott or Tru-Fire. I've used both and had good luck with them. Currently shooting a Scott Silverhorn and I really, really like it. http://www.bowhunting.com/shopping/Products/Scott-Silver-Horn-Release-Buckl__4003B.aspx
I do use a tru fire right now but this one by Scott is what I would buy if I was in the market. I really think its the best to keep you at full push pull draw. http://www.bowhunting.com/shopping/Products/Rhino-Xt-Release-Ncs-Handl-Strap__4001NS.aspx
It's all personal preference; I had a Tru-Ball shortNsweet, didn't like it too much so I use a Scott Wildcat now and love it.
Second this, I have thousands of shots through mine and its holding up great. I will get a new in the coming weeks and it will probably be the same one. Thats how much I like it! It is personal preference though, what works for some might not for others. You could go to your local shop and see if they have a couple you could try out. Most shops do.
I used to shoot a True Fire but have since switched to a thumb release. I shoot a Stan Shootoff 3 finger. The quality is amazing and won't even think about switching back!
By far my favorite releases have been Tru-Fire. Unfortunately, most of the other other brands don't even fit around my wrists. I currently have the hurricane buckle foldback, but my favorite was the edge buckle foldback. The smaller calipers and size in general is fantastic. I'm a big fan of the foldback feature too.