I assume they continue to sell at least decently, as both are available on Amazon.uk. I don't think he was actually asking for the best-selling titles, however, because he says "There really doesn’t seem to be true Marvel evergreens, at least as far as sales are concerned", and goes on to ask "What material, if any, do you consider evergreen? If nothing, why do you feel that is? What has the potential to reach this status?" So I think the OP knows that Marvel don't have anything in the same league sales-wise, but is asking what material does Marvel have that you consider has that potential, given a little push. For me, those two stories do.
Well, that's how I interpreted it. The OP might want to chime in and clarify matters if he/she feels I'm dragging us down the wrong path.