So there are various targets as a mage that you can aim for in initiation. You can be stealthy, you can be harder to nail with spells, you can draw power off of background count. Now with trying to hold back on constant initiation (lets say 5+) what do you think constitutes the best types of builds.
For the stealth mage I would say the must buys are flexible sig., Masking, Extended Masking, and Cleansing.
For a ritual head exploding mage or a summoning mage I would say Centering and Filtering does nicely, or Centering and Geomancy. Great Ritual is nice if you have a group of ritual spell casters. Sympathetic link is also nice.
Defensive mage is of course shielding, reflecting, and absorption.
For the mage that is about to be totally boned you take masking, and flux. Flux is actually not a bad spell if you decide that you need to change your astral identity and have spirits of man sustaining your buffs instead of spell foci.