Fana > Smite > HS > Foh > Shock is how it used to work in d2lod.
Typical:
17% > 15% > 2-4 damage > Base foh damage > Synergy boost
Mix of foh and holy shock is nice, but dont foreget conv.
Smite is anyway more relatative in pvp than foh, foh is absorbed and stacked.
I haven't bothered using conv. The range is short and doesn't increase with level. Have you had much success w/ it? Most of the time that I use FoH the enemy isn't even on my screen