I've had experience with the Pac 1200. I've seen the other two. Since you're set on only those three, I'd go with the Scadden. Mostly based on the tubes (since it's truly the most important part of the boat). Has a higher handling capacity then the rest (which is important, even if you only plan day trips). The other two are fine. But in end, your stability and trackability is all based on your tubes. I know Dave has had some hard times, but he has been in the business awhile, and doubt is going anywhere soon (since he revamped his line of boats). I'd assume you're looking in the $2200 range for Dave's as well. It has the best handling capacity at 900#'s. You may think that you won't use that much. But the higher your boat floats, the easier it is to handle on the water. Put 400#'s on a 600# capacity boat and you're nearly taxing out the limits of the boat. But, you put same weight on a 900# capacity and boat will ride higher in the water, making it easier to maneuver.
Just remember, you do get what you pay for in these type of boats. Don't shave a buck and go with the lesser models. There is a new Fly Fish America out at your local fly shops that tell about pontoon boats and compare their construction. Will be an eye opener on the different boats on the market and prices associated with them. But I'd go with the Scadden, I've tried the Outcast, didn't care much for it fishingwise, to narrow of frame for that big of boat. Have only looked at the Bucks, looked ok but nothing to write home about. But did like the looks of the new scaddens. Of course, I prefer other boats.