I used both Stewart's epoxy primer, which I liked, and Eastwood's rattle-can epoxy primer, which is okay. The Eastwood is certainly convenient, if expensive and wasteful.
Stewart's epoxy has had people comment about it being hard to apply. I found it quite straight-forward and had no real trouble. Like I said, I like it.
Can't comment on durability or fluid resistance, though, for any of these.
My landing gear legs are Azko's green epoxy primer, and it's durable.
One thing that might not matter to you, is that both Stewart's and Azko's (no info on Eastwood's) can be epoxied to, and will develop a structural bond. For me, that was a plus on the main gear legs, because of the wooden stiffeners. But I haven't gotten that far yet.