It also has a passive ability that makes it incredibly safe to use: As long as The Aetherspark is attached to a creature, The Aetherspark cant be attacked and has Whenever equipped creature deals combat damage during your turn, put that many loyalty counters on The Aetherspark. With the right creature, you could be drawing two extra cards a turn, or you could simply make it easier to ramp up its ultimate ability
And which should win really depends on whether you value the impact back at the time or their longevity
Like most Magic: The Gathering cards, the value of Phyrexian Scriptures depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (The List)
It doesn't matter what the casting costs are , so a two mana summon can wind up turning into a powerful nine mana one (although the inverse is also true)
Jace is a much better Planeswalker when his abilities focus on mind magic