I've got the Stearns Inflatable One Man kayak and it's the best option for fly fishing. The exterior shell is extremely tough as is the inflatable shell. I use it on the Cape, North Shore, Maine, and Boston. It gets dragged, car topped, hooked, and scraped every time I use it and it is still in great condition. The inflatable portion is never exposed to the elements because of the outer shell. It packs into a duffle bag and weighs under 30lbs. The zippable spray skirt/cockpit enclosure makes a great stripping basket. Overall the kayak is stable, durable, lightweight, and versatile.
The only drawbacks are 1.if you are a fairly large person and 2. It tracks poorly. I'm 6'1 and 220lbs and I squeeze into the cockpit. If I'm in it for more than three hours I get slightly cramped. You can always unzip the enclosed cockpit portion and hang your legs out if this happens though. Tracking is like any other Kayak under 10', poor. Poor tracking helps when you're fighting a big blue and headed on a Nantucket sleigh ride though.
This thing was just the answer for me. When we pack the car for a weekend or vacation I needed something I could put on the roof rack along with other stuff. When you put a rigid kayak on the roof rack it doesn't leave room for much else, especially if it's short and beamy. I researched a lot of these and was about to buy an Innova Helios when I found a Stearns for $150 at REI-outlet.com. The Helios had more room and tracked very well but it cost around $550. Also looked at the Aire's and Soar's, BIG $$$. The material was quite similar to the Innova and they had a broader range of colors but they also didn't look like they'd work well in the Northeast under a fair amount of chop.
Sorry for the long winded response but I researched a lot of these things.