Watershed seems to make the most superior drybag, to echo everyone else. Are the Futa bags the ones with the airbag valves built into them making them dual purpose as drybags/airbags? If you have walls in your boat (like most) then you should consider investing in TWO of the tapered models.
Me? My Eskimo boat is admired by some and ridiculed by many. But there is no wall, nor is there a need for one. Here's my set up and it works great:
I have two air bags for bow and stern, each custon designed to fit the interior of my boat. It takes up all the space except for the cockpit zone I occupy.
I don't have any Watershed bags 'cause I'm a Dirt Bag with no money. If I was packing a video camera I'd get a small one for that.
Instead I use a variety of various shaped drybags a varying sizes and styles. I have found that I can dial in my load with these to an incredible level of precision.
The Bow: I pack some lightweight stuff like tarp and ground cloth, maybe a garbage bag into a tapered cone shaped, cheap drybag. I pack it in front of my footbrace bulkhead, then inflate the airbag underneath it so it is pressed up tight against the deck, keeping it out of the water that barely finds its way up there.
The Stern: The airbag in my stern sits toward the back as I load one or two medium sized drybags, like a Sealine roll down and a cheap ass Seattle Sports dry-duffle with a purge valve and the little clear window (t's not %100 dry, but close enough). These two bags get placed as tight behind my seat as possible. They contail my sleeping bag, pad and clothes, in addition to my Patented jPak-A-Boat back pack system.Then I inflate the rear airbag and it takes up the rest of the space in the back and prevents the load from moving around.
Hip area: Dude, the way I pack all of my basic survival incidentals that follow me on most trips I take in my creek boat is
Totally Hip: A very small drybag on either side of my seat carries most of the stuff listed in the "Rescue/Bailout" thread we were going off on about a year ago
http://www.professorpaddle.com/forum/forum_posts.asp?TID=7815. These bags are carefully balanced to weigh symetricly.
Foreward of my seat: I have a central spot for the waterbottle and throwbag like a lot of boaters. I also rigged up a small bungy net on either side of the boat between the bulkhead flanges and the seat. More small bags sit here under my thighs for my food, ect. I rigged this because that space is unobtrusive to my entry/exit from the craft, and the weight sits closer to my seat where you want it. I found the whole "Drybag Between The Legs" thing to be a liablity. When you are in some class V canyon and you need to get out abruptly, what do you do with the bag each time you get out to scout? How about those turbulent micro eddies where you need to claw some vertical rock with fingernails to get purchase just to get out of your boat?
"Drybag Between The Legs" syndrom sucks.

Nevermind having to exit your boat from a pin Like Packy Cronan On the Clarks Frk of the Yellowstone ("Packy's Crack", as the infamous seive is now named- I was there when it happened and he could have died)--How about simply loosing your foodbag because it was between your legs and you had some hairy scramble getting out of your boat and lost the bag?
Anyway, off topic perhaps slightly. But the point I am making in my signature Verbose way is this:
A variety of shapes, sizes and styles may suit you better than simply zeroing in on the dryest bags. If your boat isn't a huge leaker and your skirt is also fairly watertight, your bags will stay pretty dry if you are thoughful about how you pack your boat, and how you pack the bags. Just something else to consider.