Actually, of the ones on your list, there's surprisingly few I'd put on a list like this. Of the ones you've got up there, I'd go with nova, chaos seed, and pillars/pends. A few others off the top of my head:
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= lobotomizer
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= wyrm, flying weapon, dragonfly
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= gargoyle, dusk shield
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= bone wall, arsenic, poison, flesh spider
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= graboid, pulverizer, titanium shield
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= antimatter, pandemonium, chaos seed
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= rain of fire, fire shield, fire bolt, lava golem, immolation

= sapphire charger, gravity shield
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= horned frog
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= miracle, holy flash, guardian angel
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= electrum hourglass, procrastination, sundial
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= arctic squid, blue crawler, trident, steam machine, toadfish
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= shard of sacrifice, shard of serendipity
My reasoning is as follows:
1) cards that get a quanta cost reduction of more than 1 (ex: miracle, rain of fire, antimatter, procrastination, etc)
2) cards that become 'other' or zero cost cards instead of elemental cards (holy flash, sundial, flying weapon, dragonfly, etc)
3) cards that gain a significant attack/defense increase for no extra cost increase (gargoyle, lava golem, horned frog, sapphire charger, flesh spider, etc)
4) cards that become significantly more useful at no extra cost (arctic squid freezes an extra turn, shard of sacrifice costs 8 less hp, shard of serendipity gives upped cards, etc)
5) cards that even with a cost increase become significantly stronger enough to more than warrant said cost (blue crawler, titanium shield, poison)
6) oddball upgrades (chaos seed, toadfish)
I'm at work so I can't actually see a card list right now, but the reasons stand, even if my lists are incomplete.