I'm only including trinkets that I think are truly GOOD for resto druids. There are some that are decent, and perhaps even good with odd gear or spec combinations, but my list is based on what the majority of raiding trees will be looking for. My personal preference is normally towards reliable trinkets, where the effect is not based on a chance proc or on use. I don't always get my wish, but you may find this list biased that way just a little =)
Let me mop up a little drool here...
First, the haste use effect is very nice. I've been hoping for a reliable haste trinket, but an on use is not a bad choice here. What makes this trinket truly amazing is the mana restore, which procs off of EACH TICK of our heals, including overheals. According to a WoWHead commenter,
for example: means wildgrowth with glyph gives 6 targets a hot which ticks every second for seven seconds:A 6 target healing spell that costs less than 200 mana? *fwibble* Unless I get to the gear point where mana is insignificant and my haste is higher than I'd like, I'd consider this one of the BiS trinkets. And one of the best things about it, this trinket drops from one of the 5 man heroic instance. Anyone should be able to obtain this, so good luck with the drop =)
wildgrowth = 643 mana
trinket returns: 7 * 6 * 11 mana = 462 mana
Nevermelting Ice Crystal
This one I'm a little iffy on still. It's easy to obtain, dropping from one of the 5 man heroics, and has a decent amount of spell power. While the on use effect is going to be pretty underpowered in most situations, with 4pc T9, it becomes vastly more appealing. For a tree with the 4 set bonus that's not having mana issues, this could be a very nice trinket, but I think I'll be leaving it taking up bagspace myself. I honestly expect to see the CD on the use lowered a bit, or perhaps the effect itself buffed slightly, but even then it's not quite as appealing in most situations or gear levels.
Depending on how this proc works, this is either going to end up being a BiS trinket for many, or a very situational trinket. IF this can proc from WG, IF it is a smart heal and will try to land on someone that actually needs the health, or IF the internal CD is reasonable, this could be great. Unfortunately, there seem to be too many unknowns still. At worst, this will be something I'd pick up to use on heavy raid damage fights. At best, I'll be fighting most of our healers to try and pick it up. This looks to drop from 25 man Gunship battle, so it will be available with the first stage of the content release, but hopefully we'll see some testing results soon.
Show of Faith
Or any of it's previous incarnations (Je'Tze's Bell, Sif's Remembrance). This has been a popular trinket model for all of Wrath, but lately I've been seeing more and more trees replacing it with different choices. That said, it is still a good trinket if you're lucky enough to find one available. The Show is from 25 Yogg +1 or +0, Sif's is off of 10 Thorim HM, and the Bell can be picked up off your local auction house for a few Kg on most servers. This provides approximately 65-80 Mp5, so keep that in mind when comparing against your other options.
Solace of the Fallen
In comparison, the normal version of this trinket provides a reliable 128 Mp5. The heroic version is even more amazing, but not everyone is lucky enough to have that available *Innocent whistle* If needed, the normal and heroic versions of this trinket do stack, but most of us won't need that much Mp5. It is a very very shiny trinket, and most 25 raiding guilds are killing Jaraxxus on a pretty regular basis, so not the most difficult to obtain.
Spark of Hope
Even though spirit is no longer the chocolate that it was for us trees, it is still one of our most powerful stats. The Spark grants about 20 spellpower and 250 mp5 for us, and while it's not one of the best trinkets out there, it is a decent choice for a 10 raiding resto, or a tree that's having some serious mana issues.
Gnome... It's what's for dinner.The Unmentionables
Now, time for a little fun. These next two are trinkets that are currently not quite nice enough to make my list, but I'd not be shocked to see changed.
Purified Lunar Dust
Currently, compared to even the normal version of the Solace, this is a pretty disappointing trinket. If it ends up having a 45 second CD, even with the 19 iLvl difference this is going to give lower Mp5 and only 3 more spell power. I expect to either see this buffed pretty significantly, or the internal CD made very short. That said, it is obtainable through Emblems of Frost, which will make it a decent choice for some raiders.
Sliver of Pure Ice
Currently, the Mp5 from this trinket will typically match what you'd be getting from the Show of Faith, and that's only if the player is activating the use effect on cooldown each time. Even if it does end up getting buffed to be competitive, I'm not particularly fond of the mana pot type use, but it could end up being a decent option for 10 man raiders. As of this writing, it seems that it's drop location is still unknown, so it may end up that this trinket isn't even available for a good while after the first stage of Icecrown Citadel opens.
"Khi, just quit jabbering and tell me what trinkets to pick!"
Well, it's always going to depend on your gear, spec, the encounter, and you're role. That said, basic ideas...
Nevermelting Ice Crystal
Solace of the Fallen