2. One player determines the forces and mission and let's the opponent pick a side.
No. I didn't spend years of work and huge amounts of money building
DKoK so that I could let someone else use my army. Plus, I don't trust anyone with my models.
3. Devise a "default" list for each race that are intentionally balanced against each other. These lists could include units not traditionally fielded so long as overall balance is preserved.
No. Not only does this remove the creativity of list building entirely (and along with it the ability to play games against a variety of opponents) it also kills any motivation to buy new stuff. Why spend more time and money on a new tank when I won't be allowed to use it in my "default" list? That just isn't fun at all.