think an EJ9 shell is a good choice. it's not too old for having lot of rust and problems, almost same base as EK9, and you get plenty of parts for it.
It's cheap as hell too. of course an EG shell would be a little lighter and probably eaven cheaper, but less safe and probably more rust and stuff..
If your not in a hurry then go for an ek9 mate, in the future when and if you do want to sell it atleast your car will be holding a lot more value or you could get a px for a much newer car, k swaps are getting cheaper by the year, also I say ek9 are more rare and you will have something different