Except for the digital lotteries, I see no reason to give TodayTix the fees they charge when all it seems they're doing is applying discount codes at the box office for you and giving you your ticket later.
If you're a student (or, in some cases, under 30 or 35, depending on the show's policy), student rush is easily worth investigating as the prices will likely be best there (subject to availability and whatever hoop you have to jump through.) TKTS is the best choice if Student Rush isn't a good option, and TodayTix just seems like a well-oiled scam. But lord knows you see enough baiters phishing their discount codes looking for a bite (notice how many of them are still waiting for someone to bite? If they had been used already, they wouldn't be here.)
Words don't deserve that kind of malarkey. They're innocent, neutral, precise, standing for this, describing that, meaning the other, so if you look after them you can build bridges across incomprehension and chaos. But when they get their corners knocked off, they're no good anymore…I don't think writers are sacred, but words are. They deserve respect. If you get the right ones in the right order, you can nudge the world a little.