I took the liberty of lightening and cropping your pic.
With what you have, formal upright probably is your best option. To get good proportions, you'll want to preserve as many low branches as possible. So I would pinch back the new growth on the upper half of the tree, getting more aggressive as you go up.
In case you're unaware of this, Colorado spruce have a well-deserved reputation for poking back! But they can make nice bonsai if you're willing to put in the time.