Amalgam is hands down one of the best, if not the best, trinket for Holy right now. You'll most likely want to use it for one slot.
For your second choice, it depends whether you want throughput or another regen. Personally I prefer a second regen trinket as Holy is not terribly mana-efficient with constant FH spam being our main playstyle. Having said that, I use "Fluctuating Energy" from Karazhan as my second trinket.
Other good options right now:
- Ephemeral Paradox (Regen, Nighthold)
- Etraeus' Celestial Map (Throughput, Nighthold)
- Brinewater Slime in a Bottle (Throughput, Helya)
- Ethereal Urn (Throughput, Nightbane)
- Darkmoon Deck: Promises (Regen, Darkmoon Faire)
- Unstable Arcanocrystal (Throughput, World Boss)
Naglfare Fare is not a terribly good trinket, even with Mythic +12. The effect just isn't worth it really. The shield will more than likely be gone in under 2 seconds in most situations.
Hope this helps