We can't use the automatic one because we're in the water all the time.
I would be worried about maintaining the manual CO2 one.
The oral inflation one would be good to have, if you get injured/stuck out/etc etc and you are able to inflate it.
I tried on a bunch of kayaking pfds and they were all horrible. Uncomfortable and way too much crap on them.
I ended up buying one of these.
It felt fairly comfortable and was not too expensive at $150. Now I just have to remember to wear it. I would not wear a PFD for general kiting. I bought it for doing long solo coastal runs so I just have to make sure I wear it when there is a chance for a coast run.