1 Cyberdark Edge
Most collectors, I imagine, would go for shadowless over 4th print (UK/8th print/etc.) and when youre dropping significant cash on 4th print, you might as well go for 1st edition if you havent done it yet
Combat Research is a weaker version of Enduring Curiosity's effect, since it only applies to one creature, but also gives +1/+1 and Ward 1 to a legendary creature , providing a little protection for your commander
Damaged starts at $62, with a slight bump in price for heavily played (HP) to $80, followed by MP cards fetching about $113 and LP cards capping the top-end at $285
In-game, you will stack the Xyz monster on top of the cards tributed and, more often than not, can then use the materials to trigger certain card effects from the summoned monster