the new vero 29s (gen 7) should be, but i'm not sure they're in stock yet, might be a couple weeks still. from what i understand they don't bin, unlike cree, which means that you might get a chip that underperforms relative to datasheet (but also one that overperforms). either way, gen 7 vero 29s look like really good cobs.
the citizen clu048-1812 and clu058-1825 are probably the most direct competitor for the 3590. the 1812 matches it and is cheaper, the 1825 beats it at about the same price. there's also the clu048-1212 which isn't quite on par, but is so cheap you could more than easily match a 3590 for less money. as far as citizens go, none of this is true for digikey, which is very expensive for some reason. citizen makes great tech but they have weird business practices.
either way, if you're comfortable with costs of 3590+proven track record, go for it. you're not going to be saving or upgrading by very much, whichever you go with.
poke around the diy section, there are more knowledgable posters than me over there.