Pick one sub and one amp you would use to push it if money weren't an issue. Space would also be unlimited. Heck, even describe the car/truck it would go in.
Also, again, money not being an issue, post up your ideal set up including subs, amps, box size, how the box would be tuned and any accessories you would add like batteries, alternators, etc.
This should be fun. Hey we can all dream can't we?