So many Oscars don't like tank mates and they tend to tear up everything in the tank so that you can't have a nice looking/attractive tank which seems to me disappointing. They are very beautiful fish with interesting color variations but I personally wouldn't have one for the above reasons.
They probably require a humongous tank to be happy. IMO not worth having such a huge tank for one fish, seems like so much empty space better used other ways.
I bet you could find some other pretty amazing fish to keep in a nice 90. I have seen some astonishingly beautiful fish AA people keep!