2
Expanding Aequitas's answer there's also:
Garden Gnome: Increases Luck, effectively increasing damage inflicted and reducing received.
Bast Statue: Increases defense by 5.
1
While it will depend on your difficulty, equipment, and what you intend to do, Warding (+4 defense) and Menacing (+4% damage) are popular modifiers for all accessories that can be reforged.
In terms of what the game considers best, based on the effect of the modifier on the item's price, there's a 5-way tie:
Warding (+4 Defense)
Lucky (+4% Critical Strike ...
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