If a key piece like Storm-Kiln Artist or Jeskai Ascendancy gets answered, you might lose your momentum
The quotes under the pictures are from his facebook page btw, and all of them from the last month
With that much effort put in, most players are looking to get more out of it than a 6/6 flample that might or might not remove something
Any time you attack with any creature, they gain both first strike and renown 1, meaning if they deal combat damage to a player, if theyre not already renowned, they gain a +1/+1 counter and become renown
Im not going to parse out the best or worst ones here, but they all kind of fit the description
It should have higher defensive abilities