I used plasti kote. almost five years now and they still look like the day I painted them, no flaking or fading what so ever. And they see the sun everyday out here in Cali.
i used the rust-oleum fabric and vinyl paint and was amazed by how it looked it looked like they were brand new and i heard to use the flat colors because the gloss can cause the sun to reflect harshly
I haven't actually tried this, but from what research I have done the flat (Landau) vinyl dye by SEM stays really well and keeps the original factory texture. It's like $10 a can, just make sure to degrease and clean the panels thoroughly first or oils and build-up will stop the dye from taking.
I used Krylon. It has held well, but there are a couple places where I have scuffed it back down to original green. Not a fault of the paint. The plastic was "krunchy" and flaky, very oxidized. I didn't want to knock all the oxidized plastic off because I would lose the "leather grain" that is molded in to it. before and after...