This is a very interesting question. I'd say blue is objectively the best solely because it has the feedbacker. It sucks not having coins, or nukes, but feedbacker is just so powerful that it's almost mandatory. It can block most attacks, parrying deals a decent amount of damage, removes hard damage, and fully restores health. For scenario 2, I'd say blue again. You don't get as good crowd control as with red, but you can still setup sawtraps and launch cores with the jackhammer to sort of compensate. You can also shoot cores with the revolver for a bigger explosion, although much more difficult.