[Ender]

Here's what I've heard/read:
People have had good success with the regular Atkins seals, just make sure you clearance them (as you should ANYWAY, but some people think "Hey, they're new so I can just throw them in the motor and they'll work right." That's not always true, clearance your seals and you won't have to wonder if they're right or not. Plus, housings (especially used ones) differ in thickness, which is a big reason you have to clearance your seals.)

I've heard that the Rotary Aviation seals are harsh on the housings, that the housings take more of the wear than the seals, and you want it the other way around.

I would bet you wouldn't need the one piece seals, but they would probably work ok (however I don't know much about the one piece design versus two piece). They may not seal quite as well as the two piece design, but they might be slightly more durable. I honestly don't know for sure though, and just look at Kevin Lander's FC build to find out how important it is to use the newest, most expensive, flashiest sounding products.

Personally, I used new Mazda OEM apex seals with an Atkins kit for everything else. Unless I was going to build a really cheap/expendable motor or a crazy high power output motor (like 500+rwhp on a 13B) then I'll stick with Mazda OEM. They pretty much know their shit about rotaries.

Ceramic and carbon seals are available as well as different treatment options, but they're also usually pretty expensive. I think it's highly cautioned against to turbo a motor with carbon seals, too.