Top (CTRL to add secondary) 3
They have strong sizes to casting cost, a strong ability when they are on the battlefield, and when they die they turn into their Temple, which taps for their mana and then heads back with a tap at sorcery speed but with a harder to do activation
Burning-Tree Emissary has made it more tempting to splash but then you don't have to take much of a downgrade on your sex monkey to stay in colour
Lifeline Be sure you understand the oracle text on Lifeline
If another effect (or effects) modifies how much damage your creature with a +1/+1 counter on it would dealby preventing some of it, for examplethe player being dealt damage or the controller of the permanent being dealt damage chooses the order in which any such effects (including Uncivil Unrest's) apply
Obviously the spread isn't the same on all cards (this is especially true of low-value cards), so the way you come out ahead is trading ten cards that retail for $1 (but sell for $0.50) for one card that retails for $10 (but sell for $7), or by trading three $50 cards that sell for $35 for one $150 card that sells for $120