I don't know why, but right now I prefer to play BO1. In BO1, I would like to have access to Fae of Wishes (especially since I've already put some effort into constructing wishboards for Fae of Wishes). Fae of Wishes is very mana intensive and I don't want to play Temur Clover, hence ramp, hence Simic.

Cards I'd like to play:

Fae of Wishes - obviously
Uro, Titan of Nature's Wrath - obviously
Incubation Druid - what's weird about this card is that people seem to be playing little, if any, interaction. Incubation Druid is then something of a ramp spell that can be adapted, plus the synergy with ...
Lotus Field - idk about this. I started playing this card because of this article. It wasn't great then, but it did do some powerful things. Lotus Field also allows all five colors in the sideboard, which greatly increases the options.
Discontinuity - if I'm playing with Lotus Field then presumably I need this card. It's OK with Uro too.
Ugin, the Spirit Dragon - this is probably the best catchup card now, even better than Mass Manipulation.
Mass Manipulation - an old favorite. Not as good if I'm firmly behind, but if the board isn't too overwhelming it's still good at stabilizing, it's more backbreaking than Ugin @ 8 mana, and it can be cast at 6 mana too.

Cards I'm not sure about:

Nissa, Who Shakes the World - it's not like she's bad, she is a strong ramp spell, but she needs to live.
Elvish Reclaimer - it can tutor Lotus Field, but it's hard to make this a 3/4, and Uro shrinks it too.
Voracious Hydra - I somehow never see this card anymore even though it's still legal. It's a reasonable interaction spell.
Hydroid Krasis - I tried it a bit but I'm really not sure, because it's only good as a ramp payoff and I already have some extremely strong ramp payoffs.
Shark Typhoon - same as Krasis.
Kiora, Behemoth Beckoner - if she gets to untap Lotus Field then great, but what if she doesn't?

Cards I probably need:

Arboreal Grazer - turn 1 ramp, unless Gilded Goose is better, but everyone else is playing Grazer so ...
Cultivate - it's ramp, and it also gets cards into hand to discard to Fae of Wishes. It's not been bad, but it's possible there are better cards (but again everyone else is playing it ...).
Elder Gagaroth or Cavalier of Thorns - to stabilize the board since I'm going to be solidly behind much of the time. The former is better at stabilizing, the latter keeps up the ramp + fuels Uro.

Sideboard cards:

More Mass Manipulations & Ugins - sounds reasonable
Kiora Bests the Sea God - this should deserve a slot. It's a good generic wish target and doesn't take Lotus Field to play.
Sublime Epiphany - when instants are needed, I imagine. One problem is aside from Cavalier & Uro (who's not likely to be on the battlefield), the other creatures don't have ETB effects.
There're loads of other options: Chandra, Shatter the Sky, Casualties of War, etc. I suspect cards that take 2x non-green non-blue mana, such as the Mardu ultimatum, would not be playable though (since they'd take 2x Lotus Fields or Incubation Druids to play).

Lands: currently playing 28. 27 might work, but I find I want to make land drop after land drop and so far it's rare to flood.

What I like about the deck so far is that it overpowers most things in the late-game, it has lifegain to stabilize against aggro, and Fae of Wishes provides versatility against almost whatever the opponent is doing. What I don't like about the deck is how easy it is to get run over. If opponent has a 1-2-3 curve for example I can be pretty near dead before I can drop one of the 5-mana cards like Elder Gagaroth or Cavalier of Thorns, and then a removal spell wins the game. I also can't interact with Winota, who's bull**** and I think should be banned too because of how random it is (I still nearly stabilized against an opponent who drew 4 Winotas in top 17 cards, but on the last turn they had Embercleave).

I'm sure there are lots more cards I have not figured out, so if anyone out there better than me at deckbuilding can chime in, please do!

Maybe something like this, but with Fae instead of Haven.

https://www.mtggoldfish.com/deck/3283115#paper

I run 27 land, started at 31 but flooded way to often, for the ramp suit I got 4 Grazer, 4 Druid, 4 cultivate, the new 3 cmc elf dork that draws when ETB and a couple Solemn Simulacrum.

This way you put blockers into the board while ramping.

Pay offs: 2 Krasis, 4 Nissa, 4 Ugin and 2 Teferis to dig and fuel Uro.

Thanks Darkstar. That deck runs Questing Beast which I find rather weird, but interaction in the form of Brazen Borrower or Aether Gust is likely necessary or this deck deterministically loses too often against an aggro deck on the draw.

Not convinced Solemn Simulacrum is right - sure it's a blocker, but it's not a good blocker, and it's a 4-mana ramp spell. The deck really wants to be playing ramp on turns 1-3. How's it been working for you? Elvish Visionary seems rather similar, Uro is pretty clearly better and Cultivate should be better as well.

I feel like Discontinuity is pretty clearly missing Wilderness Reclamation. If Wizards had chosen to ban Expansion//Explosion instead of Reclamation I would certainly play that. As it is, I'm not sure if it's too cute. Casting it on opponent's turn is rare, and if that doesn't happen then it's a pure combo piece. Nullifying the sacrifice trigger on Lotus Field has come up decently often (it happens less than 50% of the time for sure though) and the interaction is very powerful; on the other hand nullifying Uro's sacrifice trigger is much rarer since it takes five mana. I did get one game where I played Uro, dropped Field and then Discontinuity'd both triggers - that was amazing.

It also feels like other decks have ways to beat this one even in the late-game. I lost a game to Temur Clover Flinging a 14/14 Giant + Expansion on the Fling. Clover itself seems like a tough matchup. If they have a Clover, then the deck is very vulnerable to Brazen Borrower bounce and getting tempoed out. Not having Krasis also makes it hard to race, on the other hand Krasis doesn't seem like a good ramp payoff (Ugin / Mass Manipulation are better).

It's possible this deck is just subpar, although I am (slowly and painfully) climbing the ranks in BO1.

Just played this game from the monored side. I'm on the draw.

Turn 1: we both land go.
Turn 2: he plays land, Wolfwillow Haven. I play land, Runaway Steam Kin.
Turn 3: he plays land, Cultivate (up to 5 mana). I play land, Runaway Steam Kin #2, Tin Street Dodger.
Turn 4: he plays Nissa, untaps a land, attacks, Elder Gagaroth (!). I play land, activate Tin Street Dodger, hit him for 1, Light up the Stage, Anax. (Exact memory gets hazy here, but essence is there)
Turn 5: he plays land, cracks Wolfwillow Haven, untaps a land, cannot attack since my two Steam Kins would eat his Elder Gagaroth. On my turn I play land, activate Tin Street Dodger, attack. Embercleave the Anax, Nissa dies. He concedes to the 10/3 double-striking Anax.

I'm beginning to be very skeptical of Simic Ramp because of games like this one. His draw was insane, but he lost anyway. Simic badly needs more interaction, but there's none to be had in those two colors. One would have to add a 3rd color for sweepers, at which point one might as well be playing Sultai. I'm ready to bench this deck as a result in favor of tuning a Sultai list for BO1 play.