I'm not a top-100 player, but I think I know enough about the game to hold a discussion.
My personal style is a severe and heavy focus on TSpin-double setups: TKI3 and Albatross. But I "respect" other players who have taken the time/effort to try other strategies, and I even see the advantages of their setups.
> and in reality I think fancier builds like DT-cannons are too fragile and reliant on a clean-ish stack that they're not even viable in high level play.
But players I respect and study are extremely strong with DT-cannons. Doremy and Amemiya (especially Amemiya) use DT cannons regularly. The "Amemiya Cannon" is the famous DT-cannon + perfect clear / DT-cannon + TSD option select (depends on RNG) for example.
> Third option is comboing.
Amemiya does both. DT-canon leaves the "z" shape overhang ready for the most reliable side-4w builds. Side-4w is more risky, but provably faster to build than center-4w.
After all, bag-randomizer is still... somewhat random. If the pieces aren't setup for one possibility, you need contingency plans. I'm sure top players like Amemiya is constantly looking ahead and deciding upon "DT-canon + Perfect Clear" and/or "DT-canon + side-4wide" depending on what the RNG-blesses him with.
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I've also had the pleasure to play vs Wumbo on multiple occasions. A lot of people complain about Wumbo's absurdly fast comboing skills, but in my experience, Wumbo is also a top-tier player in simple TSpin-double setups.
> If you're not too technical, you need be fast at tetrises and hope you can outpace your opponent.
IMO, Tetris only works as a downstacking strategy. Especially since guidelines tetris often has "clean garbage" (if you deal 7 damage from a B2B TSpin Triple, your opponent will have all 7-garbage lined up and ready for a counter-Tetris to erase 4-of that garbage).
As an upstacking strategy, Tetris is pretty weak. You require 10-pieces (40-minos) to build a Tetris, but only deal 4 damage+B2B, maybe 5-damage at the best case. Pretty bad all else considered.
As a downstacking strategy, Tetris requires zero-pieces to setup (assuming garbage is lined up), removes 4-lines of garbage from your side, retains B2B bonus, and deals 4 damage to the opponent. That's a garbage-conversion of 9 total and zero-pieces of investment.
In contrast, TSpin-singles (favored by Amemiya, especially vs Puyo players) require only 1-lines of upstack, one of which can be from garbage (!!). A singular Z or S piece is all you need to setup a TSpin-single that digs into your garbage and digs downward. (-1 garbage line, one-piece of upstack, B2B bonus retained, 2-damage + B2B for a 3rd damage). That's roughly 4-converted damage with only 1 or 2 pieces used, and the king of efficiency.
3-lines of damage that requires only 2-pieces (s/z + T) and digs into garbage is extremely solid. That's 2-pieces dropped and a conversion of 4 lines, far more efficient than an "upstack-tetris" (10-pieces dropped and a conversion of 5-lines, assuming B2B bonus)
In a pure upstacking scenario: TSS, TSD and TST are all far more efficient in a "pieces per garbage" situation. 3-lines of upstack turn into 6 damage + B2B for TST, far more efficient than 4-lines of upstack turning into 4 damage+B2B for an upstack Tetris.
King Crimson (TST + 2x TSD) turns 7-lines of upstack into 16 damage + B2B. Extremely efficient.
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So from my perspective, the game is in roughly 3 phases:
1. Opening -- Because the bag randomizer is so predicable, both players can execute pre-concieved strategies extremely reliably. It seems like c4w is the strongest strategy in the current meta, but there's some "rock-paper-scissors" play involved (I find that TKI3 / 3x TSpin Doubles in the first 3 bags is a solid counter vs enemy c4w players as well as perfect-clear players, which is why its my favored opening)
2. Downstacking -- Removing garbage from your side of the field as efficiently as possible. Tetris tends to be the best strategy, but some players (ex: Wumbo) have the ability to "combo downstack". Combo-downstack is the strongest strategy but is incredibly difficult to pull off. Amemiya's TSpin-single setups demonstrate efficiency in practice. (TSpin-single when garbage "doesn't line up", to retain B2B bonus while downstacking)
3. Upstack -- Once you "reach the bottom", you need to build the stack back up before you deal damage. Tetris is a poor option for Upstack, but dedicated builds (King Crimson, Super Tspin double, etc. etc.) perform the best in my experience. Bonus points for "Bursty" builds like King Crimson or DT-cannon, because many players hold onto a "Defensive Tetris" to cancel out some of your upstack damage in this situation. So you need a plan to reliably deal in excess of 9-lines of damage to the opponent.