I think the best way to look at it is, to simply look at them as if they where old cpu's so just look at it as one is dual core, the others are quad core.
Then go from there. So therefore if these where s775 cpu's, would you have gone dual core or quadcore?
If you would have gone E8's then go for the I3, if you would have gone for the Q9's then go for the I5 7's.
hope this makes sense lol