[quote name='pete5883']If you can wait, play P3 for PSP, then 4. If you can't, play FES then 4. The improvements in 4 make it harder to go back to 3, but 3 Portable will be better than FES.[/QUOTE]
I seriously doubt that. At most, it's going to be the same game just with an option of going female as MC. It's also cut down in terms of navigation with everything now being handed to you, outside of Tartarus that is, although this is more based on preference than anything else.
But the most important thing, The Answer won't be included. Sure it wasn't included the first time around, but the fact that you're missing story sucks. Then again, if he has FES he can just always play Answer there.
To answer your question OP, play 3 then 4. Playing 4 first won't let 3 feel as great as it's suppose to and if you move up from 3 to 4, you're appreciate the improvements.