To me the priority list goes (assuming you have 15 on every class already, like you said ) :
1) Byregots Blessing (50 crp)
2) Steady Hand II (37 cul) Careful Synthesis II (50 wvr)
3) Ingenuity II (50 bsm) Comfort Zone (50 alc) Innovation (50 gsm)
4) Name of Element (all classes but cul/gsm 54) Makers Mark (54 gsm) Reclaim (50 cul)

So try to mark off each tier as you go. Doesn''t matter which you do in the tier first just that you complete the previous tier.