Hey folks,
Posted this in general disc, and got little to no feedback (people too busy crying about he vault, quitting etc).
I have been using feral cat, since I love the regen and the mana free damage…but what’s most important to me is the SPEED of movement. So many things in the game now involve dodging circles and getting to a spot…it’s saved me so many times.
I also find I don’t have time to sit in balance and get off a full eclipse cycle before Dps is dying 
What do y’all use?
I use guardian for battlegrounds, and feral for Torghast or solo, or for PVP if I’m feeling saucy (feral convoke with Oath of the Elder legendary is funny). I don’t do a lot of PVE, but I like feral for dungeons too, because of the speed you mention, and because I don’t enjoy the current balance play. No idea what the Very Serious Content Rule is for M+, I assume balance because it’s the best damage?
Love your name. 
I’m still using Feral Affinity for most PvE stuff. I tried using Balance Affinity for a bit, and did reasonable DPS pretty much on the strength of Boomy Convoke alone. The thing is, the Boomkin rotation doesn’t really fit into healing intensive encounters. As Feral Affinity, you can take advantage of a few free globals to push some DPS (and remain completely mobile while doing so), but the same isn’t really true of Balance. Also, like you, I hate being slow. =P
I use feral for pve because I hate boomkin. Guardian for 3v3 or bg’s.
Oh boy, that’s a doozie of a question. The ultimate answer is “it depends”. Disclaimer: I likely represent a middle/upper-middle of the pack player. I’m 9/10 heroic nathria and just over 900 io M+ player. I also tend to take pride in my DPS parses as a healer.
Cat Affinity: I never take this anymore… For a while I used this affinity on the Artificer fight for the run speed as an aid for phase 3, but since improving my play I NEVER use it. It was once the meta to “cat weave”, but I wasn’t able to pull good DPS that way without comprising my positioning or neglecting heals past the point I should.
Gaurdian Affinity: I occasionally use this. An example where I use it most of the time is for pvp and specific nathria boss fights. An example would be Sledgefist. I personally found the damage reduction useful so I could focus on raid healing more effectively and worry a little less on my own HP (gardian damage reduction + barkskin on every pillar) and focus on others, such as our shadow priests that get slapped hard by the 3rd and 4th pillar slam. I seldom take this affinity for M+…
Balance Affinity: I’m in this almost always. I like it for unrated pvp fun (HotW convoke on 1v1 or group fights can be hilarious as a healer). I cant say enough good things about typhoon!!! When it’s used poorly, it can be super annoying in group play and cause more problems if used with poor discretion, but it’s clutch when you’re needing that extra second for your kiting tank to drop stacks of narcotic, or push a caster out of a sanguine pool, or push adds from necrotic wake bosses/plaguefall boss adds into better positioning, and and and… Furthermore, with the Titan legendary, you can cast both regrowth AND life bloom in boomkin form! Last week, I ended the 1st boss of a Mist 12 at 3.1k DPS with zero deaths and not leaving moonkin form but once or twice for a couple rejuves; and that was without HotW (I took mass roots on that one). My advice isnt to always be in moonkin form, but rather look for windows with lower damage on your fellow players and eek out those moments when they come. There are also soooo many bosses in M+ and nathria where you have atleast 15 seconds of freecasting DPS spells before any real damage goes out. Like I mentioned before, I take some level of pride in seeing a 99% DPS parse on a raid boss (obviously you dont dps when your raid is suffering and losing people due to simple rot mechanics.)
That’s my 0.02$. I’m not the best, but I’m not the worst.
Thanks for the thoughtful replies.
I think part of my bias is that I really hate the look of the moon kin form. I suppose I could buy the glyph (shrug).
Great thing about this, is you can switch and try them all. I’ll have to try guardian next.
The extra regen for cat form comes in handy, on long fights with heavy Regrowths usage (sun king). My play isn’t good enough that I can drop the cat speed 