
HumbleGamer |
Arcane tradition allows you to use the ring of wizardry, which drastically boost the spell slots you get from a standard dedication.
Apart from that, you'll be tied to the standard spellcaster dedication slot progresion ( you can choose whatever you like, without worrying about some being underpowered compared to others ).

breithauptclan |

Hmm... probably the Witch since they are given a Familiar and can automatically get another free Cantrip Slot from spending a Familiar Ability on top of the Cantrips they get out of the gate.
If we are looking for spell slots, then cantrip slots aren't quite the same.
Also, the familiar given by Witch dedication comes at a cost of a cantrip slot for the Witch - they only get to prepare one cantrip per day instead of two like most archetype spellcasters.
So with that in mind, any spellcasting archetype that has a familiar as an option generally ends up having more cantrip slots as the multiclass Witch does. Wizard, for example, gets two cantrips to start with, can pick up a familiar for one more, and can get Cantrip Expansion for another two. Witch gets one cantrip to start with, can use the familiar to get a second one, and can get Cantrip Expansion for two more. But that still leaves them one cantrip slot lower than the Wizard.