On Three Spell Spirit (a little help for a friend)

The erudite Roger over at Rolls, Rules, and Roles is onto a fairly brilliant observation, but he needs some assistance.

He's attempting to pare the spell list down to six first level spells and three spells of each level following.

But which spells!?

The post is here, go and comment. I think discovering what the crowd wisdom is over which spells are essential and not is going to be quite interesting.