I agree with the previous posts.
In my experience there aren't good options for toting supplies on the FS bike because you don't have the ability to clamp between the rear hub and the seatpost.
There are seatpost-only attachments (such as from Delta named "Postporter" maybe?) but that puts more weight up above & behind the suspension. I wouldn't advocate hanging a bunch of groceries there or anything with weight to it.
The best-reviewed full-suspension-bike cargo solution is one of the
B.O.B. trailers. It attaches to your rear hub, requiring only that you remove your skewer.
As for the bikes. It really really does depend on what yclo said. Plus ...
- what repair option you want to do. (mail-order & self-repair, or give to shop w/instock parts, for example)
- how often are you willing to have it that it needs to be maintained? (For example, usually the more complex the rear linkage, the more frequently it needs maintenance.)
- what's the application? Rocky trails? Hills? Mountains? Flatland typical of Dayton? Just mainly road riding but with lots of potholes?
- etc.
Also, at 270 I'm thinking you might want to look at the freeride bikes because they'll be less spindly and also offer adjustable and mucho travel to ease your back pain. Plus they tend to have metal-spring shocks. (Steel or Ti) I'll just be dogmatic and say you'll only be swearing at a blown air shock, front or rear. The air's would need more frequent maintenance too. Go for metal springs as the main shock components.