I can't say for sure what is the best, but I can tell you what worked for me.
I just looked at the Konfidence suits (never heard of them) and I wouldn't use it at first. It doesn't appear to have any way of stopping the child from tipping forward, so until they can balance on their own, they will be forever falling over.
What I used when my daughter was a toddler was a suit that had basically an inntertube built into it. It gave her freedom, when she jumped in it popped her right back up, and unless she was really trying it kept her from going face forward. If you get a suit like this, keep it out of the heat. We went through at least one suit a season - the rubber dries out and eventually will stop holding air.
I've noticed a couple different kinds of the suit I am talking about are available now. The one I had was a full suit. I saw one the other day that was just the top part of the suit - an innertube with a fabric cover and arm/head holes. If it had a crotch strap I would be more comfortable with it. It seems like it would be easy to slip out of.
The suit like the Konfidence ones - we had something similar after the inntertube suit but by that time we were moving onto swim lessons and water wings.