[Autotune]

Charisma matters for enchanter
No stats matter for necro charm.

MR debuff/s will help both.

Necro undead charms by themselves are completely random (except the one charm with fixed duration).

Enchanters have stronger charms, due to charisma and having MR debuffs.

Edit: As far as duoing with a cleric, if you're strictly facing undead mobs and aren't going after extremely difficult undead mini bosses at that, the necro will outperform an enchanter all day long.