As requested:
First off: some might consider this list spoilers. It's a high-level view, but it does "give away" some of the dynamics of each Spirit, which some folks might prefer to discover through exploration.
Secondly: please take this list with a grain of salt - for a variety of reasons ("having two young children" being among them) I didn't play much Spirit Island between development wrapping up at the end of 2015 and the retail release in June. I mean, I've played 15-20 times since then, but certainly haven't played all the Spirits yet. So my recollection of some Spirits' dynamics is much fresher than others!
All that out of the way:
Lightning's Swift Strike: Unusual. Its phenomenal Card Plays track + powerful innate would normally make it extremely Play-tilted, but it has multiple obstacles to going that way - including not enough Energy to flog its starting cards.
River Surges in Sunlight: Tilts towards Plays. It can get new Power Cards with ease and the Reclaim One spot makes it great at that.
Shadows Flicker like Flame: Balanced. It's good either direction (or mixed), and can adapt readily to either style.
Vital Strength of the Earth: Leans towards Energy, just because its track is so good… but, unusually for an Energy-leaning spirit, not towards a huge number of Major Powers, because three of its starting four Power Cards cost 3, and because its Reclaim option is so strong that it can just flog one or two over + over. (Also, it really wants to reach 2 Card Plays at some point, unless it's packing a truly titanic and effective-even-without-thresholds Major Power - maybe Fire and Flood or something.)
A Spread of Rampant Green: Balanced. I've seen play-heavy Rampant Green blasting out minors and triggering top levels of both innates, and my last play of Green I think I took something like 4-5 Major Powers. Of course, at least half the time it opens up its full Presence Tracks anyhow…
Thunderspeaker: Tilts towards plays. Has a harder time getting lots of them than Lightning does, but an easier time gaining Power Cards.
Ocean's Hungry Grasp: My recollection is "it really depends on the game" - more specifically, on the % of the players who are going to make feeding it a moderate priority (and to some extent on the Energy cost of Power Card acquisitions).
Bringer of Dreams and Nightmares: Tilts towards Energy + Major Powers.
Heart of the Wildfire: My recollection is "balanced". It's super-good at Energy generation once it uncovers a lot of Fire. And it's super-good at burning things in its lands once it plays lots of cards / has lots of fire. (IIRC, though, healing Blight tends to require veering towards Plays.)
Serpent Slumbering Beneath the Island: Unusual; the crossed Presence track means it has an early-game choice, then must go balanced, then a late-game choice.
Sharp Fangs Behind the Leaves: Tilts towards plays. (Though it has the elements early on its Energy track to trigger Ranging Hunt even with its base of 2.)
Keeper of the Forbidden Wilds: Tilts towards Energy + Major Powers.
Trickster Watches with Many Eyes : Tilts very heavily towards Plays - it's really good at gaining Minor Powers (and needs to), plus Stir Up All Manner of Trouble benefits from a wide swath of Elements. It still has viable paths that include Energy/Majors, though!
Also, writing the list, I realize how often it depends on situation: what other Spirits are in the game, what Adversary you're playing against, what you draw for Power Cards, what Events have shaped your position, etc.