This was my first deck. It is now mostly retired, since no one wants to play against it (I've beaten friends teaming up 3 or 4 on 1 against it, so I can't blame them either). I managed a few T2 wins with it (with or without this exact build), and when that fails, I can consistently draw and play the entire deck on T3.
Sadly, there are no Legacy or Vintage competitions in my area (that I know of, anyway), where I could play this, and I'd probably need to invest in some cards to be up to tournaments' standards, but as far as casual play against friends is concerned, Elves decks are as fun and versatile as MTG gets, in my very own biased opinion. Well, there's also Slivers, but fuck Slivers, right?
Anyhow, the current incarnation of the deck includes...
Fyndhord/Llanowar/Priest for mana,
Shaman/Messenger to draw,
Ranger/Symbiote/Seeker/Lodge to untap,
Timberwatch/Commander/Voice to win and
Pendelhaven/Hollow/Symbiote to counter removal.
I decided not to play Modern cards with it, but stuff like Umbral Mantle, Joraga Warcaller and Immaculate Magistrate have been played in this deck and were great fits, but completely unnecessary and overkill.
Same with Collective Unconscious, which I personally like over Messengers and Shamans, since they allow to draw non-Elf cards too, and in greater number, but for the sake of having as many Elves as possible in the deck, I took those out, long ago.
Other great cards like Gaea's Cradle, Natural Order and Glimpse of Nature would also work great here, but once again, I can do without them, not to mention they're worth more than the entire deck currently is.
Obviously, stuff like Stasis, Planar Collapse or any cheap/target all removal and counters can slow this deck down, but in the end, Elves always prevail. Even if they know that the Timberwatch is the main winning condition, if they let everything live and wait for it, they'll still lose.
This is by far the deck I spent the most time tweaking, and with which I had the most fun through the years. It literally spawned 3 other Elf decks I initially started with cards I acquired for this deck, but which ended up inspiring me different ideas.
Concordant Crossroads can be replaced by Lightning Greaves to make this more budget-ish.
I'm usually hoping for something like 2x Forest, Crossroads, 2x Llanowar/Fyndhorn, Priest, Messenger opening hand, then to draw untappers.
Turn 1. Forest, Llanowar/Fyndhorn
Turn 2. Forest, Crossroads, Llanowar/Fyndhorn, Priest, Ranger/Symbiote/Seeker (untap-tap Priest), Messenger (draw 2-3 Elves), another Ranger/Symbiote/Seeker (untap-tap Priest), Timberwatch, Shaman (tap to draw more), then swing with everything that isn't tapped once I can't play anymore creatures, buff what isn't blocked with the Timberwatch (multiple times if untappers are still available). Should be about game over, depending on how lucky I get with drawing more Elves.
Some times, it's better to take things slow... No point getting anything out if I'm not going to use it during that turn, especially the Crossroads, I really don't want to let an opponent benefit from it before I do. Likewise, some times, it's better not to use a Symbiote's ability just to untap. Instead, I can bring vital cards back to my hand before they get killed by some opponent's attempt at not losing. I can also always use the Symbiote's ability to return a Messenger to my hand so I can cast it again during my next turn, or the best, returning a tapped Priest to my hand to untap a second Priest, so I can then play the first again, untapped and re-tap both for mana... "Use this ability only once each turn." also happens to lose most of its meaning in multiplayer games and/or when 4 of them are out...