Stocking foot if you are going to be in areas that is rocky just for the ankle support. If it is just a beach and you don't have to walk far then boot foots.
My problem is finding a pair that FIT well. I'm not built like a normal person (whatever that is .... lol) so comfort is important to me since I usually have to walk in a ways.
I went with a pair of West Branch waders by LL Bean. WHY?! - they fit me the best, are very comfortable and I know LLB will take care of me if I have leaking issues.
I would highly recommend TRYING the pair one before you buy them if that is possible.
You can always order 3 pair and keep the ones that are the best if you have to do mail order.
Sit, crouch, stretch and lean in every physical way you can get your body to bend with the waders on - make sure they FIT. Get a neoprene wading belt and a pair of SOSpenders for insurance. Cost on the inflating life vest has come down considerably over the past couple of years - you can get most for under $80 (best money well spent IMHO). Do you want to see your kids grow old and meet your grandchildren some day?!
I have a pair of the older style Guide Weight Gore-tex Simms boot foots that I got in a trade last year. Best boot bottoms I've ever seem - don't think they use the same ones now - if you can find old stock check them out. I've been in sticky mud and they don't pull off like my other ones I had owned in the past. Simms are $$, but all the saltwater fly guides I know use them - that has to say something.
If money was no object I would go for the high end fancy Simms G3 Guide Waders in stocking foot (~$550 w/ studded boots).