On our last boat we had a West Marine/Zodiac 10-footer, with the High Pressure air floor. I thought this was ideal for a motor-powered tender. Very fast and easy to set-up/store, no parts to lose, fast and maneuverable, and stable underfoot.
But if you ever want to row, you need a rigid hull. For my current boat I picked up a used Walker Bay 8 because it was cheap, durable, and lightweight. There's no way we're going to store a dinghy outboard on this boat, so rowability was the primary concern. The WB 8 doesn't row like a whitehall, but it does as well as most hard dinghys, which is to say, it gets you to the beach and back. I don't find it tippy, personally. Towing it is fine, in moderate wether, and it's light and easy to hoist onto the foredeck using a spinaker halyard. (In heavy weather or offshore you shouldn't be towing any dinghy, IMO.) I've seen the towing eyes ripped out of more than one inflatable dinghy, so I'd worry about that if you plan on towing a lot. Also, I never tow with an outboard on the dinghy. The weight really increases the drag of the dinghy on the tow-line and dinghy hardware. A friend of mine once lost his dinghy and motor that way, because the fairly stout tow line broke in a blow.
If one of your requirements for this boat is as a makeshift lifeboat, you want an inflatable. There's nothing safe about an 8' hard dinghy in any sort of waves. So, if you want a rowable/motorable dinghy, that can provide you with a little peace of mind as a possible short-term liferaft, I'd say you need an RIB inflatable.