I personally prefer the 4 finger styles....I too went and shot a bunch of them and based on that, I felt like the 4 finger style fit my hand the best. Some of them I had a hard time loading onto the d loop...might have just been me not being use to them, and none of them were really that hard to do...but some were a lot easier to just pick up and load for me.
I do like the Carter brand releases. I just didn't find one of their thumb trigger releases that I liked. I didn't get to shoot every model they have...but did shoot a few that the shop had. They were the Chocolate Addiction, the Hammer, and I think they had a Just B Cuz too.
I shot a few TruBall models and ended up buying a ST360 by them. It was easy to load on a d loop and felt comfortable in my hand.
It wasn't until after I got one that I began reading up on them. Seems some people are having trouble with the 360 series, and the screws coming loose, resulting in the head part of it flying off. LOL not the best confidence thing in the world for me to read about. Thus far mine has held up though.