This is a loaded question, much like anchors, batteries and tow trucks. In my opinion it depends, depends on how you'll use a dinghy and how often. Is it for emergencies or for regular use? Hypalon will wear better the PVC but is more expensive but well worth the extra money. Whether you use a Weaver fold up dinghy davit system or a Hurley system where the dinghy sits flush with your swim platform the dinghy should not be wider then your 10 foot R31 beam in order to negotiate locks and docks without running your dinghy into either. Soft bottom, vs fiberglass hard bottom or aluminum hard bottom again depends on how you will use you dinghy and the depth of your wallet or desire......there is no wrong answer, all work just fine, you need to make the proper dinghy fit according to your wants, needs and desires. Defender usually has great prices and service on dinghies and outboards.
Jim