i wouldnt consider any of them to be in the least bit hardy or easy.
what size tank are these going in? they will all outgrow your 90 if that is the one you are htinking of IMO.
I would say Queen or Emperor but none of those are really hardy or easy, but as others have said will grow FAR too large for your 90 and will pick on the Volitan. As for hardy big Angels Korans, Frenchs, etc are hardier but still have the space constraint. Hope this helps!