I won't go into too much detail on the ones I don't use; I see the merit in them for people with different play styles and preferences, but there are a couple that I'm just not interested in personally.
If you're looking for a good comparison of all of the glyphs, check out 4haelz and Elitist Jerks.
Instead, this is more about the glyphs that I choose and why - which tends to be the general flavour of most of my posts - who needs math and science when you've got anecdotes, right? :D
In the beginning, there was Rejuv
Glyph of Rejuvenation. It seemed a good idea at the time, but I was swayed mostly by the fact that nobody HAD the other good glyphs yet. So, Rejuv was it.
I suppose it served me well for a little while, maybe procced a few times on Patchwerk or something. It really is more of a PvP glyph than PvE; I could probably count on one hand the number of times that A) my target dropped below 50% health AND B) Rejuv was able to tick more than once before the target was topped up by someone else.
You could probably argue that the extra 500hp or so (stab in the dark here) helped, but in the grand scheme of things, a major glyph that gives your target an extra 500hp a handful of times in a raid.... is not so great. The slot is definitely better filled by other glyphs available to us. I place this glyph firmly into the "better than an empty slot, but not by much" basket.
Resto staple: Glyph of Swiftmend
Almost every resto druid has this one, no matter what other combination of glyphs they have. This is the glyph I couldn't wait to get my hands on pre-expansion because it was just so yummy.
Before this glyph, one of two things would happen when you Swiftmended your target:
1) you would lose your HoT and have to reapply it, meaning that a) you're using extra mana, and b) you just lost a valuable HoT ticking on your tank. My rejuv, fully buffed, ticks for around 2k. That's a sizeable chunk of healing that you're losing, and fewer HoTs on your target means fewer safeguard against big spikes. Letting a HoT drop, or in this case consuming it, is a big deal if your target is taking big damage.
2) you would consume someone else's HoT and they would be cranky at you. I think we can all agree that if there are two or three druids in the raid, it is VERY handy to be able to have all those HoTs ready to Swiftmend if needed, but we've all had someone "steal" our Rejuv that we intended to Swiftmend.. it's frustrating!
With this glyph, your HoTs are not consumed, meaning you don't drop your ticks and you don't need to reapply - your HoTs can run their course. This usually means a much smoother HoT rotation because everything can run for its entire duration. It means less mana spent because you're not reapplying after a Swiftmend (and a GCD saved for the same reason).
It saves mana, it saves time, and it keeps your HoTs up while giving your target a direct/emergency heal. It really is a fantastic glyph to have.
I must say though, it takes a while to get out of the habit of re-casting a Rejuv immediately after Swiftmending!
I waited impatiently for this one to show up on the AH.
Although it was originally a 50% boost, 20% is still very nice. It not only boosts the direct heal portion of your Regrowth but the HoT ticks as well, so recasting it on your target will increase the ticks to be more substantial (note: this effect does not stack with subsequent applications).
Add in Regrowth's innate 50% crit rate from Imp Regrowth (combined with Nature's Grace for fast heals), the bonus heals from Living Seed (if you have it), mana cost reduction from ToL and Moonglow, the lengthening of the HoT timer from Nature's Splendor and the increase to healing over time spells from Emp Rejuv, and Regrowth becomes a great little tank heal option.
You can either "spam" Regrowth if you need direct heals on your target, or let the HoT run its course, but be ready to cast another Regrowth to counter sudden spike damage if needed. It's easier now to do this between refreshing your other heals - Nature's Splendor gives you plenty of time to cast Regrowth a second time without overwriting the HoT, and coupled with the Swiftmend glyph you won't be accidentally removing Regrowth prematurely.
Regrowth is definitely my staple direct heal, but if you're interested in the pros and cons of using Regrowth vs our other direct heals, Phaelia from Resto4Life has written an excellent article comparing them, taking into considerations various talents and glyphs also.
The last slot
This is where it gets hard. Most people will pick two major glyphs and then have problems deciding on their third. I had trouble picking between Glyph of Innervate and Glyph of Lifebloom.
When Lifebloom was nerfed, many people declared it was now "useless" in its new state. More expensive and less effective, you shouldn't waste your time casting it, many said. Certainly I think that is the case for raid healing - it used to be a decent spell to toss around if the raid was taking damage. It's very weak for that now, but still a great buffer to put on people who are taking consistent damage (ie, the tank/s, usually). My lifebloom ticks for around 1200-1300 buffed and runs for 9 seconds with Nature's Splendor - that's a really solid buffer on my tank/s and I still value that. An extra second would add a lot of healing and flexibility in my rotations.
So, the glyph was a "maybe" - extending by a second would mean more time for other heals, or the capacity to heal more people. But I hadn't really needed that so far in WotLK; I wasn't rolling HoTs on a bunch of people at once, and I wasn't feeling stretched in my rotation.
I was feeling the mana pinch, though, at least at first. I think for a while I was sitting at just over 200mp5 and it was hard. So I went with the Glyph of Innervate, and, as a lot of druids have said, I said that I would probably swap to Lifebloom when I got more regen.
That time came - quite quickly, actually - but I didn't want to give up Glyph of Innervate, it was so nice to have. I certainly don't need it anymore; it's rare that I struggle for mana, and I often don't pot or Innervate. But.. *cling*!
The decision was made for me though, when we started doing Sartharion+3 on 10 man. I have to be a lot more mobile, heal several people at once, and sometimes slip just out of range of the tanks for a second or two. Having one extra second on my rotation would mean flexibility to fit in extra direct heals on the tank/s, toss a raid heal, or not lose the tank if he steps a yard out of my range or vice versa.
The difference felt enormous, I couldn't believe it. You wouldn't believe how much of a difference one extra second on your Lifebloom makes. It really feels like you have forever to refresh it.
So, my new combo is Swiftmend, Regrowth, Lifebloom. I suppose I'll have to wait and see what kind of mana issues they throw at us in Ulduar, but I think this super long Lifebloom would be very hard to give up.
If you've been sitting in the Innervate camp and your regen is pretty solid, I really suggest you test out the Lifebloom glyph and see how it feels. Everyone's style is different, but if you play like me and like to keep full HoTs on one or two people and spot heal, that one little second is going to make a huge difference. Give it a try!