Any empire we create is bound to have issues, but that doesn't mean it'll be just as bad. Lelouch doesn't really desire to oppress anyone, so you're not going to end up with entire races of people being relegated to second class citizens. He'll use people as tools towards his ends, sure, but he's going to have to build an empire that is in some fashion ideologically opposed to Britannia and adheres to that in most cases.
Also, our empire only has to be more unique than Britannia. It could be law that nekomimi Mondays is a thing, with all citizens are encouraged to wear cat ears on Mondays, which on top of other things would probably meet the condition for uniqueness. Cultural uniqueness is basically one way to accomplish the condition, and we have Milly to help with that - imagine if all schools were run like Ashford Academy, with all the insanity. The Yozis would be super pleased.