If you're planning on staying at one of Universal's 3 resorts, definately do disney first.
Having front of the line at Universal is wonderful & such a change from the lines at Disney (even with fast pass). We did this last year & walking on all the rides & never waiting for restaurants was the perfect way to end our vacation.
We also found that the Portofino Bay was much nicer than the Boardwalk Villas. (Don't flame me here).....Much better service & nicer rooms.