If Not This Then Stringify
I love IFTTT (If This Then That), but although it usually works well, it's more and more common for triggers to fail. Sometimes they don't fail, but take several minutes to activate. When you want a light to turn on as you enter a room, several minutes of delay clearly can be a deal-breaker. I'm not sure if the problem is capacity issues or individual API problems, but I no longer feel confident that IFTTT will fire reliably. Although it's still in beta, Stringify aims to be more reliable, but also more robust.
(Screenshot from Google Play Store)
With IFTTT, simplicity is king. You have a single trigger (If...) and a single action (then that...). With Stringify, you have "flows", which allow multiple results along with conditionals. Basically, you write a logical flow of triggers and results using the same sorts of triggers and results IFTTT offers. Granted, the number of connected services is significantly smaller, but the number is growing all the time. There's also no web-based interface for the Stringify building process, which bums me out. I would rather have a big screen to build flows, but it's only possible to manipulate your account on a mobile device (Android or iOS).
It's not clear whether Stringify will end up being more popular and/or more reliable than IFTTT. It certainly has the promise to surpass the usefulness of IFTTT though. At the very least, the idea of competition likely will make both services strive for excellence. (Perhaps IFTTT will need to add another "T" and become "If This Then These Things!")
Stringify uses the idea of building "awesomer" ideas on top of already awesome ideas. Give it a try, and see if you can push the service hard enough to stress its reliability. I'm hoping it proves to be a viable alternative to the already awesome IFTTT!