I usually carry 25 discs in a variety of weights/speeds/plastics, and it depends on the type of course as to which get used most often.
Wooded course: straight-to-understable slot (rotation of) Opto Core/GL Claymore/Lucid Evidence, stable-to-overstable slot Lucid Verdict, anything over 300' Neutron Inertia.
Open course, non-windy day: Neutron Wave, GL River, Lucid Thief.
Open course, windy day: (all max weights) GL Havoc, Opto Saint, Lucid Verdict.